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CVE-2026-127029

Freeradius: stack-based buffer overflow via unbounded eap-sim identity length

  • High 7.5

Description

A flaw was found in freeradius's Extensible Authentication Protocol Method for Subscriber Identity Module (EAP-SIM) module. When handling authentication requests, the server copies a client-supplied identity into an internal structure without properly checking its length against a fixed-size buffer. An unauthenticated remote attacker can exploit this issue by sending specially crafted EAP-SIM messages, triggering a stack buffer overflow that crashes the service and results in a Denial of Service (DoS).

Key facts

Published
12 Nov 2026
Last changed
13 Nov 2026
Assigned by
redhat
EPSS
0.602% likely to be exploited in the next 30 days, higher than 49.385% 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-SIM submodule in the FreeRADIUS configuration if SIM-based authentication is not required: 1. Edit `/etc/raddb/mods-available/eap` (or `/etc/raddb/mods-enabled/eap`) and comment out or remove the `sim` configuration block within the `eap` module definition: ``` # sim { # } ``` 2. Restart the FreeRADIUS service to apply the changes: ``` systemctl restart radiusd ``` Warning: Restarting or reloading the FreeRADIUS service will temporarily interrupt active RADIUS authentication requests. Clients relying on EAP-SIM authentication will no longer be able to authenticate. Additionally, restrict RADIUS UDP traffic (ports 1812 and 1813) to trusted Network Access Server (NAS) IP addresses using firewall rules to limit exposure to untrusted networks.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: unknown
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