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Response snapshot Nov 3, 2026, 21:16 UTC

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VulnerabilityCVE-2026-64551

Linux kernel: sctp: validate STALE_COOKIE cause length before reading staleness

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.

At a glance

Exploited
Not known
Severity
9.1 Critical (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-64551 (opens a new tab)

What happened

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)));

Continue reading

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.

Scores and how they were measured

CVSS base severity

9.1

Version 3.1As of

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-64551 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, November 3). Linux kernel: sctp: validate STALE_COOKIE cause length before reading staleness (CVE-2026-64551). https://kevwire.com/record/CVE-2026-64551

MLA

"Linux kernel: sctp: validate STALE_COOKIE cause length before reading staleness (CVE-2026-64551)." KEVWire, 3 Nov. 2026, kevwire.com/record/CVE-2026-64551.

Chicago

KEVWire. "Linux kernel: sctp: validate STALE_COOKIE cause length before reading staleness (CVE-2026-64551)." Last modified November 3, 2026. https://kevwire.com/record/CVE-2026-64551.

Evidence summary (plain text)

Linux kernel: sctp: validate STALE_COOKIE cause length before reading staleness (Jul 27, 2026).
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.
CVSS 9.1 (version 3.1; evidence as of Nov 3, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-64551).
Sources:
NVD CVE-2026-64551: https://nvd.nist.gov/vuln/detail/CVE-2026-64551
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-03T18:06:04.789Z&lastModEndDate=2026-11-03T19:40:57.574Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-03T17:35:57.416Z&lastModEndDate=2026-11-03T19:05:57.748Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-03T17:01:00.112Z&lastModEndDate=2026-11-03T18:35:55.788Z&resultsPerPage=500&startIndex=0
Record ID: CVE-2026-64551.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Nov 3, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

NVD status: Awaiting Analysis. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

Record detail