---
id: CVE-2026-31696
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  rxrpc: Fix missing validation of ticket length in non-XDR key preparsing

  In rxrpc_preparse(), there are two paths for parsing key payloads: the
  XDR path (for large pay…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  rxrpc: Fix missing validation of ticket length in non-XDR key preparsing

  In rxrpc_preparse(), there are two paths for parsing key payloads: the
  XDR path (for large pay…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-787
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 3.17, < 6.6.136'
  - 'linux_kernel >= 6.7, < 6.12.84'
  - 'linux_kernel >= 6.13, < 6.18.25'
  - 'linux_kernel >= 6.19, < 7.0.2'
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.2
published: '2026-05-01'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:19:17.777'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-31696'
references:
  - url: 'https://git.kernel.org/stable/c/1fa36cf495b0023e8475d038535c05e4063211e1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/41a117dd80371343babc52198d1114e83eb37627'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4458757c020592a3094366e0fb20457383b42f92'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/44714dfda386884919ba366411880b6fb3c3efd3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9a397aa9b5e53ca63d4d6aefb542832eca389618'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a1be1c9ece26cea69654f28b255ff9a7906b897b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ac33733b10b484d666f97688561670afd5861383'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ce383ba615339f8eaec646a166d2c2b015bb5ca0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-784472.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00176
epssPercentile: 0.06635
ingestedAt: '2026-10-15T03:30:12.865Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

rxrpc: Fix missing validation of ticket length in non-XDR key preparsing

In rxrpc_preparse(), there are two paths for parsing key payloads: the
XDR path (for large payloads) and the non-XDR path (for payloads <= 28
bytes). While the XDR path (rxrpc_preparse_xdr_rxkad()) correctly
validates the ticket length against AFSTOKEN_RK_TIX_MAX, the non-XDR
path fails to do so.

This allows an unprivileged user to provide a very large ticket length.
When this key is later read via rxrpc_read(), the total
token size (toksize) calculation results in a value that exceeds
AFSTOKEN_LENGTH_MAX, triggering a WARN_ON().

[ 2001.302904] WARNING: CPU: 2 PID: 2108 at net/rxrpc/key.c:778 rxrpc_read+0x109/0x5c0 [rxrpc]

Fix this by adding a check in the non-XDR parsing path of rxrpc_preparse()
to ensure the ticket length does not exceed AFSTOKEN_RK_TIX_MAX,
bringing it into parity with the XDR parsing logic.

## Affected

- `linux_kernel >= 3.17, < 6.6.136`
- `linux_kernel >= 6.7, < 6.12.84`
- `linux_kernel >= 6.13, < 6.18.25`
- `linux_kernel >= 6.19, < 7.0.2`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.2`