# CVE-2026-64551: CVE-2026-64551

Status: published. Published: 2026-07-27. Updated: 2026-11-03.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

Not reported in collected sources.

## Severity and prioritization

- CVSS 3.1: 9.1 (critical); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H; source: NVD: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable yes; technical impact partial; source NVD SSVC: 134c704f-9b21-4f2e-91b3-4a467353bcc0

- Weaknesses: CWE-125

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/08a8f2d13f703924316e9aeac863a88ef50990c7 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/1cd23ca80784223fa2204e16203f754da4e821f8 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/588706ebaf8cdb4a4161602949eba365514b1db1 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/6022da37786701df1fc5dd946a6dcba59d5473b1 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/861f884f5471632c731cbbd612a1c072e391a624 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/a257b41ddfe9e327b26581ad2777f04b23ac73f5 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/bbd6b2ea966cf57b6ae095cf5a8dbc993cd197a0 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/ebe0a55d954fa8da383b6192edb8f763dcb002d5 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

## Provenance

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64551; retrieved 2026-11-03; source updated 2026-11-03

Revision: 2e131b3243a6ef30fdab18b2c5c4621e985c128bd9f16b81710d87f5a7f97c74

Canonical: https://y2.dev/cve/CVE-2026-64551

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