CVE-2026-80521: af_unix: Unlink scc_entry in unix_del_edge().

mediumCVSS 4.7CVE-2026-80521

CSIRTS triage

vendor: Linux product: Linux Kernel Memory corruption

What: The af_unix subsystem fails to properly unlink scc_entry when deleting an edge, potentially leaving stale references in memory.
Who is affected: Systems running affected Linux kernel versions with af_unix networking in use.
Urgency: Medium priority; not currently exploited but medium CVSS score indicates potential for denial of service or memory corruption.
Action: Apply kernel security patch when available from your Linux distribution.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 4.7
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-80521

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-805210.12% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 2% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-80521	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for af_unix

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-80521: In the Linux kernel, the following vulnerability has been resolved: af_unix: Unlink scc_entry …nvd · 2026-08-26
highCVE-2026-63388: Libevent: Heap out-of-bounds write in bufferevent_socket_set_conn_address_ reachable via AF_UN…msrc · 2026-08-11
mediumGHSA-wh89-7897-x99h: Netty: HAProxy V1 Protocol CRLF Injection via AF_UNIX Addressghsa · 2026-07-22
highCVE-2026-64109: In the Linux kernel, the following vulnerability has been resolved: af_unix: Fix UAF read of t…nvd · 2026-07-19
mediumCVE-2026-53361: af_unix: Set gc_in_progress to true in unix_gc().msrc · 2026-07-14
unknownCVE-2026-53361: In the Linux kernel, the following vulnerability has been resolved: af_unix: Set gc_in_progres…nvd · 2026-07-04