CVE-2026-127030

Freeradius: stack buffer overflow via unchecked eap-fast sessionticket length

Published Nov 12, 2026 CVSS 3.1 · 7.5 High EPSS n/a KEV · Not listed
Description
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).

Remediation

Vendor 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.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Freeradius
Freeradius freeradius
Red Hat
Red Hat enterprise Linux
Vendors & Products Freeradius
Freeradius freeradius
Red Hat
Red Hat enterprise Linux
Type Values Removed Values Added
Description 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).
Title Freeradius: stack buffer overflow via unchecked eap-fast sessionticket length
First Time appeared Redhat
Redhat enterprise Linux
Redhat rhel Els
Weaknesses CWE-787
CPEs cpe:/a:redhat:enterprise_linux:10
cpe:/a:redhat:enterprise_linux:8
cpe:/a:redhat:enterprise_linux:9
cpe:/o:redhat:rhel_els:6
cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat
Redhat enterprise Linux
Redhat rhel Els
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Nov 13, 2026, 12:22 AM
Reserved
Nov 12, 2026, 10:45 AM
Status
Awaiting Analysis
Published
Nov 12, 2026, 5:17 PM
Modified
Nov 13, 2026, 2:18 AM
Severity
Important
Public date
Nov 12, 2026, 12:12 PM