CVE intelligence

CVE-2026-64551

Vulnerability intelligence

Published Jul 27, 2026Sources checked Nov 10, 2026

9.1CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-64551 and is rated Critical severity with a CVSS score of 9.1. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Ubuntu Security Notices guidance

Vendor revision: Oct 2, 2026

Vendor remediation details

This update corrects flaws in the following subsystems: - ARM64 architecture; - S390 architecture; - x86 architecture; - DRBD Distributed Replicated Block Device drivers; - InfiniBand drivers; - IOMMU subsystem; - Multiple devices driver; - Network drivers; - Microsoft Azure Network Adapter (MANA) driver; - NVME drivers; - TCM subsystem; - Virtio Host (VHOST) subsystem; - Xen hypervisor drivers; - AFS file system; - File systems infrastructure; - Network file systems library; - Network file system (NFS) client; - NTFS3 file system; - OCFS2 file system; - OrangeFS file system; - SMB network file system; - IPv4 networking; - Sun RPC protocol; - IPv6 networking; - IP tunnels definitions; - Netfilter; - TCP network protocol; - Locking primitives; - 9P file system network protocol; - B.A.T.M.A.

Ubuntu Security Notices guidance

Vendor revision: Sep 30, 2026

Vendor remediation details

Ubuntu Security Notices guidance

Vendor revision: Sep 29, 2026

Vendor remediation details

CISA KEVNot listedBased on the latest collected catalog

EPSS0.5%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-64551?

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.

Source: NVD