---
id: CVE-2026-64551
title: 'sctp: validate STALE_COOKIE cause length before reading staleness'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  sctp: validate STALE_COOKIE cause length before reading staleness

  When an ERROR chunk with a STALE_COOKIE cause is received in the
  COOKIE_ECHOED state, sctp_sf_do_5_2_…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    6022da37786701df1fc5dd946a6dcba59d5473b1
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    861f884f5471632c731cbbd612a1c072e391a624
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    588706ebaf8cdb4a4161602949eba365514b1db1
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    a257b41ddfe9e327b26581ad2777f04b23ac73f5
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    08a8f2d13f703924316e9aeac863a88ef50990c7
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    ebe0a55d954fa8da383b6192edb8f763dcb002d5
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    bbd6b2ea966cf57b6ae095cf5a8dbc993cd197a0
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    1cd23ca80784223fa2204e16203f754da4e821f8
  - Linux 2.6.12
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-16T15:42:25.961430Z'
published: '2026-07-27'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:52:52.000Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-64551'
references:
  - url: 'https://git.kernel.org/stable/c/6022da37786701df1fc5dd946a6dcba59d5473b1'
  - url: 'https://git.kernel.org/stable/c/861f884f5471632c731cbbd612a1c072e391a624'
  - url: 'https://git.kernel.org/stable/c/588706ebaf8cdb4a4161602949eba365514b1db1'
  - url: 'https://git.kernel.org/stable/c/a257b41ddfe9e327b26581ad2777f04b23ac73f5'
  - url: 'https://git.kernel.org/stable/c/08a8f2d13f703924316e9aeac863a88ef50990c7'
  - url: 'https://git.kernel.org/stable/c/ebe0a55d954fa8da383b6192edb8f763dcb002d5'
  - url: 'https://git.kernel.org/stable/c/bbd6b2ea966cf57b6ae095cf5a8dbc993cd197a0'
  - url: 'https://git.kernel.org/stable/c/1cd23ca80784223fa2204e16203f754da4e821f8'
tags:
  - cve.org
epss: 0.00514
epssPercentile: 0.42495
ingestedAt: '2026-10-16T17:24:46.833Z'
---

## Overview

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

sctp: validate STALE_COOKIE cause length before reading staleness

When an ERROR chunk with a STALE_COOKIE cause is received in the
COOKIE_ECHOED state, sctp_sf_do_5_2_6_stale() reads the 4-byte Measure
of Staleness that follows the cause header:

	err   = (struct sctp_errhdr *)(chunk->skb->data);
	stale = ntohl(*(__be32 *)((u8 *)err + sizeof(*err)));

err is the first cause in the chunk, not the STALE_COOKIE cause that
caused the dispatch, and nothing guarantees the staleness field is
present. sctp_walk_errors() only requires a cause to be as long as the
4-byte header, so for a STALE_COOKIE cause of length 4 the read runs
past the cause, and for a minimal ERROR chunk past skb->tail. The value
is echoed to the peer in the Cookie Preservative of the reply INIT,
leaking uninitialized memory.

sctp_sf_cookie_echoed_err() already walks to the STALE_COOKIE cause, so
check its length there and pass it to sctp_sf_do_5_2_6_stale(), which
reads that cause instead of the first one. A STALE_COOKIE cause too
short to hold the staleness field is discarded.

The read is reachable by any peer that can drive an association into
COOKIE_ECHOED, including an unprivileged process using a raw SCTP socket
in a user and network namespace.

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 6022da37786701df1fc5dd946a6dcba59d5473b1`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 861f884f5471632c731cbbd612a1c072e391a624`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 588706ebaf8cdb4a4161602949eba365514b1db1`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < a257b41ddfe9e327b26581ad2777f04b23ac73f5`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 08a8f2d13f703924316e9aeac863a88ef50990c7`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < ebe0a55d954fa8da383b6192edb8f763dcb002d5`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < bbd6b2ea966cf57b6ae095cf5a8dbc993cd197a0`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1cd23ca80784223fa2204e16203f754da4e821f8`
- `Linux 2.6.12`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.