---
id: "CVE-2026-127030"
page: "https://infrastack.ai/live/CVE-2026-127030"
kind: "vulnerability"
aliases: ["CVE-2026-127030"]
title: "FreeRADIUS: EAP-FAST length check flaw lets a remote attacker crash the server"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["eap-fast", "freeradius", "package", "radius", "self-hosted"]
not_affected_if: ["eap-fast-disabled"]
published_at: "2026-11-12T17:17:43+00:00"
first_seen_at: "2026-11-12T17:39:39+00:00"
updated_at: "2026-11-12T17:41:13+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-127030", "first_seen_at": "2026-11-12T17:39:39+00:00"}, {"source": "analyst", "url": "https://lists.freeradius.org/hyperkitty/list/freeradius-users@lists.freeradius.org/message/4WZLJAYGIDCJTZ3GFPQ3CNRJSWGPFANX/", "first_seen_at": "2026-11-12T17:41:13+00:00", "cites": ["https://lists.freeradius.org/hyperkitty/list/freeradius-users@lists.freeradius.org/message/4WZLJAYGIDCJTZ3GFPQ3CNRJSWGPFANX/"]}]
exploit_sources: []
---

# FreeRADIUS: EAP-FAST length check flaw lets a remote attacker crash the server

Link for people: https://infrastack.ai/live/CVE-2026-127030 (this .md is for agents)

FreeRADIUS has an improper length check in its EAP-FAST module that allows a stack-based buffer overflow while processing session tickets. A remote, unauthenticated attacker can send a crafted handshake request to crash the server process, causing a denial of service.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run radiusd -v; versions before 3.2.11 (3.0.x and 3.2.x) should be treated as exposed until the vendor publishes an affected range.
- Check whether EAP-FAST is enabled: grep -rn 'fast' /etc/freeradius/mods-enabled/eap (a 'fast {' block inside the eap module, and 'fast' in default_eap_type or the sites). If not used, the maintainer says you are not affected.

## Fix

Upgrade to FreeRADIUS 3.2.11 once released (announced as upcoming on 2026-10-22; release not confirmed). Fix commits: 064567a, a5d09da on GitHub.

## Timeline

- 2026-11-12T17:39:39+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-127030
- 2026-11-12T17:41:13+00:00 analyst https://lists.freeradius.org/hyperkitty/list/freeradius-users@lists.freeradius.org/message/4WZLJAYGIDCJTZ3GFPQ3CNRJSWGPFANX/ — Maintainer commit 064567a (2026-10-14, 'Fix possible stack overflow in EAP-FAST', found by Anthropic/Ada Logics) and list post by Alan DeKok (22 Oct) saying 3.2.11 'shortly' will include TEAP and FAST security fixes; not affected if EAP-FAST not used. No release page confirming 3.2.11 shipped, no affected range, and default-enabled status not confirmed; left unknown.

## Documents

- [advisory] Release 3.2.11 and security fixes (Alan DeKok, 22 Oct 2026) https://lists.freeradius.org/hyperkitty/list/freeradius-users@lists.freeradius.org/message/4WZLJAYGIDCJTZ3GFPQ3CNRJSWGPFANX/
- [fix] Patch: github.com https://github.com/FreeRADIUS/freeradius-server/commit/064567a08f3b9d9b4863fab6060fafe296ac7de9
- [fix] Patch: github.com https://github.com/FreeRADIUS/freeradius-server/commit/a5d09dad528d7a3a3c4c01158716ab85a12e09ef

## From the sources

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).

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