CVE-2026-64551

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, service disruption.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2026-07-19 15:36 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-07-27 21:17 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-11-03 18:15 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.5% in the next 30 days (EPSS).
• Severity: 9.1 CRITICAL (CVSS).
• Fix: none linked yet, which raises it.

Details

Published

2026-07-27 21:17 UTC

Last modified

2026-11-03 18:15 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-125 · Out-of-bounds read

Record status

Awaiting Analysis

Attack profile CVSS 3.1 · 9.1

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

High

Is it in your code?

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