Security Contact

The FreeRADIUS security contact is All security related information or notifications should be sent to that address. Security notifications may be signed with the pgp key

Security announcements

Multiple issues found by Guido Vranken

We requested that Guido Vranken do fuzz testing against the server. He found issues in all versions of the server. These issues are documented on the fuzzer page.

Erroneous Session Resumption

We discovered that the server could be convinced to permit TLS session resumption before the authentication finished. A partial fix was put into 3.0.13. Pavel Kankovsky verified that the fix was insufficient, and provided a tool to test the issue. A better fix was put into the server, and was released in version 3.0.14.

The original EAP-TLS code would refuse to resume sessions unless there were policy attributes in the session cache. This check was put in place to work around this issue with the OpenSSL API. At some point, the code was changed to cache policy attributes by default, which opened up the vulnerability. Given the long history of the server, it is not clear when that change was made.

FIX: The short-term fix is to disable session resumption in the cache subsection of the eap module.

We believe that this issue affects version 2.1.1 through 2.1.7 inclusive. Other versions seem to be unaffected. We remind users that versions 1.0.x, 1.1.x, 2.0.x, 2.1.x, and 2.2.x are old and unsupported. Patches for those versions will not be released, as the issue can be corrected with a minor configuration change. We also note that prior to version 3, the session cache was disabled by default, and required administrator intervention to enable it.

The v4.0.x branch is not vulnerable to this issue. The underlying code has been refactored to hide the TLS session data until the final EAP Success is sent, in the Access-Accept. This change means that the issue is impossible to reoccur in the future.

At this time, we have not had reports of the issue being exploited in the wild.

FreeRADIUS server scanned by PVS-Studio

The people at PVS-Studio were kind enough to give us a temporary license so that we could scan FreeRADIUS. We scanned the v3.0.x branch of the server, as of commit a7df94.

You can read our write-up here.

Tunnel-Password Vulnerabilities

Denis Andzakovic found issues with the decryption of very long Tunnel-Passwords. The decryption routines could walk off of the end of a buffer, and write to adjacent addresses. The data being written is not under control of an attacker. The end result is usually a crash of the server.

The initial report was for version 3.0. We determined that the v3.1.x branch in git is also vulnerable. Version 2 has similar code for Tunnel-Password, which we were not able to exploit. However, for safety, all currently supported versions of the server were fixed.

The packet decoder in FreeRADIUS ensures that the only time this issue is exploitable is when a proxy server receives a long Tunnel-Password attribute in the reply from a home server. The attack cannot be performed by a RADIUS client, or an end user. As such, the exploitability of the attack is limited to systems within the trusted RADIUS environment.

We are releasing version 2.2.9 and version 3.0.10 to correct the issue.

Revoked intermediate certificates are not properly validated

oCert-CVE 2015-4680

All versions which implement EAP-TLS, prior to 2.2.8 and 3.0.9 do not check intermediate CAs for revocation. We have put patches into the version 2 and version 3 branches to fix these issues.

We expect that this issue has minimal effect on the majority of RADIUS systems. If you are using a self-signed CA for 802.1X, this issue does not seriously affect you, as only you can issue intermediate certificates. If you are using certificates from a public CA, then your configuration already permits third parties to issue certificates which will be accepted by your RADIUS server.

i.e. The act of using a public CA cert in RADIUS can open your systems to security issues which are larger, and much worse than this one. The fix for this particular issue does not change the underlying security problem behind using a public CA.

Our analysis of the issue led us to disagree with the analysis done by oCert, and the (alleged) original vendor who made the report. We a requested a response to our analysis, and oCert refused. We requested that the public notice contain an accurate description of the issue and it’s impact. oCert again refused. After repeated messages, the response from Andrea Barisani of oCert was:

The reporter disagrees with your assessment yet cannot share details
about their setup, oCERT has no wishes to do technical support on
their setup as we just care about the reported bug.

Which is missing the point. We never asked to do “technical support on their setup”. We asked for an accurate description of the issue and it’s impact. oCert refused, whichs means that they do not, in fact, “care about the reported bug”.

We wanted to work together to come up with an accurate description of the issue, including it’s impact. It was clear that oCert was had no such goal. They saw their work as simply taking the original report, and forwarding it to a wider audience (including us).

We can only conclude that our analysis is correct, and that the original report, and the summary published by oCert is largely wrong. We can also recommend that people avoid oCert, as they are unwilling to work with authors to publish accurate reports.

EAP-PWD Vulnerabilities

The EAP-PWD module performed insufficient validation on packets received from an EAP peer. This module is not enabled in the default configuration. Administrators must manually enable it for their server to be vulnerable. Only versions 3.0 up to 3.0.8 are affected.

These issues were found by Jouni Malinen as part of investigating 2015-4 for HostAP.

  • The EAP-PWD packet length is not checked before the first byte is dereferenced. A zero-length EAP-PWD packet will cause the module to dereference a NULL pointer, and will cause the server to crash.
  • The commit message payload length is not validated before the packet is decoded. This can result in a read overflow in the server.
  • The confirm message payload length is not validated before the packet is decoded. This can result in a read overflow in the server.
  • A strcpy() was used to pack a C string into an EAP-PWD packet. This would result in an over-run of the destination buffer by one byte.


POODLE attack.

FreeRADIUS is not vulnerable to this issue. All version to at least 1.0.0 (and possibly earlier) require TLSv1.

Bash (Shellshock)

Shellshock bug.

Systems running FreeRADIUS may be vulnerable to this bug. The default configuration does not execute any external programs or shell scripts. However, administrators who have configured the server to execute shell scripts must upgrade their version of bash to a version which is not vulnerable.

Stack overflow in the PAP module

The CVE notification is CVE-2014-2015

The PAP module takes a “known good” password (e.g. Crypt-Password), and compares it to the password entered by the user (e.g. User-Password). In cases where the “known good” password was very long, insufficient input validation was performed. An administrator who controlled the password store could enter long passwords, and cause the server to crash.

Unix module allows expired passwords

The CVE notification is CVE-2011-4966.

It was found that the “unix” module ignored the password expiration setting in “/etc/shadow”. The default configuration does not use the “unix” module, so there is no issue for most deployments. However, if the server was configured to use this module for authentication, users with an expired password could successfully authenticate, even though their access should have been denied. We recommend managing users in a database, instead of leveraging /etc/passwd. The fact that a user has login access to a machine does not necessarily mean that they can use RADIUS for other kinds of network access.

Overflow in EAP-TLS

The CVE notification is CVE-2012-3547. The issue was found by Timo Warns, and communicated to A sample exploit for the issue was included in the notification.

We recommend all administrators using EAP and 2.1.10, 2.1.11, 2.1.12, or the git “master’ branch upgrade immediately.

The vulnerability was created in commit a368a6f4f4aaf on August 18, 2010. Vulnerable versions include 2.1.10, 2.1.11, and 2.1.12. Also anyone running the git “master” branch after August 18, 2010 is vulnerable.

All sites using TLS-based EAP methods and the above versions are vulnerable. The only configuration change which can avoid the issue is to disable EAP-TLS, EAP-TTLS, and PEAP.

An external attacker can use this vulnerability to over-write the stack frame of the RADIUS server, and cause it to crash. In addition, more sophisticated attacks may gain additional privileges on the system running the RADIUS server.

This attack does not require local network access to the RADIUS server. It can be done by an attacker through a WiFi Access Point, so long as the Access Point is configured to use 802.1X authentication with the RADIUS server.

We scanned the rlm_eap_tls.c file with the LLVM checker-267, taken from It did not find this issue. However, a Coverity scan did discover it.

Manually enabling OCSP has no effect

This issue is applicable only to version 2.1.11.

The CVE notification is CVE-2011-2701. The discoverer notified us and sent a patch.

The OCSP functionality in 2.1.11 could be enabled manually, but it would never mark certificates as revoked. As such, it did not behave as expected.

Since this issue requires manually enabling OCSP, it’s severity is low. The recommended solution is to upgrade to version 2.1.12.

FreeRADIUS may crash if database goes down

If FreeRADIUS depends on a database, and the database goes down for extended periods, the server may crash. This issue applies to versions 2.0.0 through 2.1.9. This issue is not externally exploitable.

The CVE notification is CVE-2010-3697.

As with many such notifications, the issuer did not communicate with us before releasing the alleged vulnerability. We also disagree with their description of the problem.

The short description of this problem is that any administrator who can (a) take the database down, or (b) disrupt communication between FreeRADIUS and the database can prevent FreeRADIUS from operating correctly. This result should not be a surprise.

In normal operation, when the server stops responding to packets (i.e. because the database is down), the NAS will stop sending it packets, and will fail over to another server. In addition, our tests indicate that this issue occurs only when the database is down for extended periods of time, and the server receives many millions of packets during that time. i.e. the problem will not occur in most deployments.

There is no possibility for privilege escalation, or access to the system running FreeRADIUS. The issue is marked “network exploitable” in the CVE database because it requires the network to be down for the attack to work.

Our recommendation is to upgrade to the latest version of the server. We also recommend that mission-critical systems be monitored. If they go offline for extended periods, they should be restarted.

Code modifications to the server can cause it to crash

This issue is applicable only to version 2.1.9.

The CVE notification is CVE-2010-3696.

The issuer did not communicate with us before releasing the alleged vulnerability, and we disagree with their description of the problem.

The DHCP functionality in 2.1.9 is not enabled by default. Enabling it requires code modifications, a complete re-build and re-install of the server, and a manual enabling of DHCP in the configuration. Further, the DHCP functionality is marked “experimental” in this release. As such, it should be used only on trusted networks.

This issue is exploitable whenever FreeRADIUS has had DHCP functionality enabled, and where the administrator has manually configured the server to accept DHCP packets. Any DHCP packet with a “Relay Agent” sub-option can cause FreeRADIUS to enter an infinite loop.

Our recommendation is to run experimental features only in trusted networks.

Apple Mac OS X server misconfiguration

CVE-2010-0524 - This issue only affects Mac OS X Server systems.

Apple had apparently configured FreeRADIUS to accept all “well known” Certificate Authorities as valid for EAP-TLS. This configuration permitted almost anyone to create a client certificate for use with EAP-TLS, which would then be accepted by Mac OS X Server systems.

We recommend that the list of Certificate Authorities configured in FreeRADIUS be audited, and kept as small as possible.

Server crash with Tunnel-Password attribute

Anyone who can send packets to the server can crash it by sending a Tunnel-Password attribute in an Access-Request packet. This vulnerability is not otherwise exploitable. We have released 1.1.8 to correct this vulnerability.

This issue is similar to the previous Tunnel-Password issue noted below. The vulnerable versions are 1.1.3 through 1.1.7. Version 2.x is not affected.

Memory leak in EAP-TTLS can cause server crash

This issue affects version 1.1.5 and earlier.

A malicous 802.1x supplicant could send malformed Diameter format attributes inside of an EAP-TTLS tunnel. The server would reject the authentication request, but would leak one VALUE_PAIR data structure, of approximately 300 bytes. If an attacker performed the attack many times (e.g. thousands or more over a period of minutes to hours), the server could leak megabytes of memory, potentially leading to an “out of memory” condition, and early process exit.

We recommend that administrators using EAP-TTLS upgrade immediately.

This bug was found as part of the Coverity Scan project.

Stack overflow in rlm_smb means admins can write to server config

SMB_Handle_Type SMB_Connect_Server.

While the summary is superficially correct, and there is a stack overflow in rlm_smb, the issue is less problematic than it sounds.

CVE-2007-0080 has been updated with our statement.

SecurityTracker Alert ID: 1017463 has been updated with our statement.

freeradius-smbconnectserver-bo (31248) has been updated to no longer claim the issue is remotely exploitable. They do not, however, include our vendor statement, though they do reference it. They also list the issue as “High Risk”, and “Gain Privileges”, which is NOT TRUE, for the reasons outlined below.

In summary, the issue is not remotely exploitable. It is exploitable by local administrators who have write access to the server configuration files. If an attacker can write to the server configuration files, they can configure the server to run arbitrary programs. Exploiting the server via a stack overflow would be unnecessary.

The solution to this “vulnerability”, of course, is to ensure that only the correct people are given write access to the server configuration files.

Insufficient input validation in MS-CHAP

A validation issue exists with the EAP-MSCHAPv2 module in all versions from 1.0.0 (where the module first appeared) to 1.1.0. Insufficient input validation was being done in the EAP-MSCHAPv2 state machine. A malicious attacker could manipulate their EAP-MSCHAPv2 client state machine to potentially convince the server to bypass authentication checks. This bypassing could also result in the server crashing. We recommend that administrators upgrade immediately.

Multiple SQL vulnerabilities

Multiple issues exist with version 1.0.4, and all prior versions of the server. Externally exploitable vulnerabilities exist only for sites that use the rlm_sqlcounter module. Those sites may be vulnerable to SQL injection attacks, similar to the issues noted below. All sites that have not deployed the rlm_sqlcounter module are not vulnerable to external exploits. However, we still recommend that all sites upgrade to version 1.0.5.

The issues are:

  • SQL Injection attack in the rlm_sqlcounter module.
  • Buffer overflow in the rlm_sqlcounter module, that may cause a server crash.
  • Buffer overflow while expanding %t, that may cause a server crash.

These issues were found by Primoz Bratanic. As the rlm_sqlcounter module is marked “experimental” in the server source, it is not enabled or configured in most sites. As a result, we believe that the number of vulnerable sites is low.

Additional issues, not externally exploitable, were found by Suse. A full response to their report is available here. A related post to the vendor-sec mailing list is found here.

Two SQL vulnerabilities

Two vulnerabilities in the SQL module exist in all versions prior to 1.0.3. Sites not using the SQL module are not affected by this issue. However, we still recommend that all sites upgrade to version 1.0.3.

The issues are:

  • Buffer overflow - A long string could overflow an internal buffer in the SQL module, and write two bytes of text [0-9a-f] past the end of the buffer. The server may exit when this happens, resulting in a DoS attack. Depending on the local configuration of the server, this may occur before a user is authenticated. This vulnerability is externally exploitable, but can not result in the execution of arbitrary code.
  • SQL injection attacks - The SQL module suffers from SQL injection attacks in the group_membership_query, simul_count_query, and simul_verify_query configuration entries. The first query is exploitable if your site is configured to use the SQL-Group attribute in any module in the authorize section of radiusd.conf. The last two queries are exploitable only if your site has user names that contain a single quote character (').

Multiple external DoS attacks

Multiple external DoS attacks exist in the server. These are related to the attacks below, in 0.9.2, but were not caught then. The vulnerabilities are fixed in 1.0.1, and in all later versions of the server. The vulnerabilities are not exploitable, but can be used to remotely crash the server.

Externally exploitable root compromise in rlm_smb

There is an externally exploitable root compromise in rlm_smb, through a stack overflow when a password greater than 128 bytes referenced by the module. The module is not built or installed by default, so we have not released a 0.9.4. This vulnerability is fixed in the CVS snapshots, and will be included in any later release of the server.

Crash upon receipt of Tunnel-Password attribute

Anyone who can send packets to the server can crash it by sending a Tunnel-Password attribute in an Access-Request packet. This vulnerability is not otherwise exploitable. We have released 0.9.3 to correct this vulnerability.

Kerberos module may grant incorrect access

The Kerberos module may grant access to a user whose Kerberos ticket cannot be verified against the server principal. We have released 0.7.1 to correct this vulnerability.

Multiple RADIUS vulnerabilities

CA-2002-06. Multiple vulnerabilities in multiple RADIUS implementations. We have released 0.4 to correct these vulnerabilities.

OpenSSL Heartbleed

Heartbleed bug.

OpenSSL has a major security issue, seen in to CVE-2014-0160. The issue mainly affects servers such as SMTPS or HTTPS, which allow random IP addresses to connect to them via TLS. Those sites must assume that all information available to the system using TLS has been compromised.

Based on further information from Jouni Malinen, it appears that both Version 2 and Version 3 of FreeRADIUS are vulnerable to the attack. It is likely that earlier versions of the server are vulnerable, too.

The problem appears to be that OpenSSL has already allowed invalid reads by the time that FreeRADIUS detects the invalid heartbeat, and closes the connection. The benefit of the way FreeRADIUS uses OpenSSL is that the attack appears to be limited to reading ~1K of data from the stack, when the server receives the malicious heartbeat. This limitation mitigates the attack, but does not remove the possibility of exposing private information.

We recommend that all administrators upgrade OpenSSL immediately.

Administrators can detect “heartbleed” attacks by looking in their logs for a message containing the text Invalid ACK received: 24. If such a message is seen, it means that the attack has been attempted. You should upgrade your version of OpenSSL immediately.

We suggest that all administrators upgrade all of their systems to a version of OpenSSL which is not vulnerable to this attack. Sites which allow random IPs to connect to a TLS server (e.g. SMTPS or HTTPS) should assume that all information available to those servers has been stolen from those systems. This information includes user credentials, keys for private certificates, cookies sent over HTTPS, etc.

We have updated FreeRADIUS (all versions) so that it refuses to start when it detects the vulnerable versions of OpenSSL.

v3.0.x - Administrators can over-ride this check by setting allow_vulnerable_openssl = CVE-2014-0160 in the security subsection of radiusd.conf.

v2.2.x - Administrators can over-ride this check by setting allow_vulnerable_openssl = yes in the security subsection of radiusd.conf.

Versions of OpenSSL are vulnerable to malformed certificates

The CVE notification is CVE-2012-2110.

We recommend all administrators using certificates with FreeRADIUS upgrade their OpenSSL to a secure version. For details, see the OpenSSL notification

We emphasize that this is not a bug in FreeRADIUS. FreeRADIUS uses OpenSSL for many of it’s cryptographic operations, and as such, is at the mercy of any problems in OpenSSL.

SSL keys may be guessable

A bug added to OpenSSL on Debian and Ubuntu systems means that SSL keys on those systems may be guessable.

We recommend that administrators using OpenSSL on Debian or Ubuntu upgrade immediately. We also recommend re-generating any SSL certificates used in RADIUS systems, if those certificates were created on a Debian or Ubuntu system since 2006.

We emphasize that this is not a bug in FreeRADIUS. FreeRADIUS uses OpenSSL for many of it’s cryptographic operations, and as such, is at the mercy of any problems in OpenSSL.

FreeRADIUS Security

Defensive Programming

All input is sanity-checked before use.

Clean code

There are no C compiler warnings in the build. Builds performed by developers have -Werror set, so that new errors are not introduced.

Builds with multiple compilers

We use GCC and CLANG for all builds. Each compiler produces a slightly different set of warnings. As seen above, no warnings from any compiler are allowed in the build.

Builds on multiple operating systems

We always build on Mac OSX and Ubuntu. We are in the process of adding FreeBSD and CentOS.

Builds are done with every single module, and multiple feature permutations

There is no portion of the server which has "code rot" because it has not been built for years.

Continuous testing

The src/tests/ directory has a growing set of tests for server functionality. These tests help ensure that new commits do not accidentally break existing functionality

Continuous integration

Commits are built and tested via travis

Static analysis (3X!)

Builds are performed weekly with Coverity. Builds are performed daily with Clang static analyzer and cppcheck. The server must build with no errors before it can be released.

These practices are not perfect. The test suite is growing, but it does not cover all of the servers functionality. As a result, the latest releases may still have bugs. The version 2 "stable" release undergoes less code churn and is the "long term support" stable and bug-free release. The version 3 "feature" release has significantly more code churn, and therefore, may have more issues than version 2