CVE-2026-127030
Freeradius: stack buffer overflow via unchecked eap-fast sessionticket length
A flaw was found in freeradius. An improper length validation in the EAP-FAST module allows a stack-based buffer overflow during session ticket processing. A remote, unauthenticated attacker can exploit this flaw by sending a specially crafted handshake request, causing the server process to crash and resulting in a Denial of Service (DoS).
Fixes and workarounds
Workaround
Disable the EAP-FAST submodule in the FreeRADIUS configuration, or restrict incoming RADIUS traffic to trusted network access points. 1. Disable EAP-FAST: In `/etc/raddb/mods-available/eap` (or `/etc/raddb/eap.conf`), comment out the `fast` section within the `eap` configuration block and verify that `default_eap_type` is not set to `fast`. 2. Apply configuration changes: ``` systemctl restart radiusd ``` 3. Limit network exposure: Restrict UDP port 1812 to authorized Network Access Server (NAS) clients using firewalld: ``` firewall-cmd --permanent --zone=internal --add-source=<TRUSTED_IP_OR_SUBNET> firewall-cmd --permanent --zone=internal --add-port=1812/udp firewall-cmd --reload ``` Caveats: Disabling EAP-FAST prevents authentication for any network clients that rely exclusively on EAP-FAST. Restricting firewall rules will block traffic from unlisted authenticator sources. Warning: Restarting or reloading the radiusd service will temporarily disrupt active RADIUS authentication processing.
Source: CNA: redhatAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| Red Hat Enterprise Linux 10 Red Hat freeradius
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 6 Red Hat freeradius
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unaffected |
CNA: redhat |
| Red Hat Enterprise Linux 7 Red Hat freeradius
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 8 Red Hat freeradius:3.0/freeradius
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 9 Red Hat freeradius
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 7.5 high |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | CNA: redhat |
| 3.1 / 7.5 high |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD: [email protected] |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://access.redhat.com/security/cve/CVE-2026-127030CNA: redhat · vdb-entry, x_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2572340CNA: redhat · issue-tracking, x_refsource_REDHAT
- https://github.com/FreeRADIUS/freeradius-server/commit/064567a08f3b9d9b4863fab6060fafe296ac7de9CNA: redhat
- https://github.com/FreeRADIUS/freeradius-server/commit/a5d09dad528d7a3a3c4c01158716ab85a12e09efCNA: redhat
- https://access.redhat.com/security/cve/CVE-2026-127030[email protected]
- https://bugzilla.redhat.com/show_bug.cgi?id=2572340[email protected]
- https://github.com/FreeRADIUS/freeradius-server/commit/064567a08f3b9d9b4863fab6060fafe296ac7de9[email protected]
- https://github.com/FreeRADIUS/freeradius-server/commit/a5d09dad528d7a3a3c4c01158716ab85a12e09ef[email protected]
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