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CVE-2026-127030

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

  • High 7.5

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).

Key facts

Published
12 Nov 2026
Last changed
13 Nov 2026
Assigned by
redhat
EPSS
0.688% likely to be exploited in the next 30 days, higher than 53.291% of CVEs (scores for 15 Nov 2026)
SSVC (CISA)
Exploitation: none; Automatable: yes; Technical impact: partial

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

  • 7.5CVSS 3.1, Highfrom the CNA (redhat)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What to do

  • 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.CNA workaround statement

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

VendorProductVersions
Red HatRed Hat Enterprise Linux 10
  • Default status: affected
Red HatRed Hat Enterprise Linux 6
  • Default status: unaffected
Red HatRed Hat Enterprise Linux 7
  • Default status: affected
Red HatRed Hat Enterprise Linux 8
  • Default status: affected
Red HatRed Hat Enterprise Linux 9
  • Default status: affected

Timeline

  1. 3 Nov 2026 Reported to Red Hat.
  2. 12 Nov 2026 Made public.
  3. 12 Nov 2026 Published

Weakness

References