---
title: "CVE-2026-80521: af_unix: Unlink scc_entry in unix_del_edge()."
url: https://erroneo.us/security/cve/CVE-2026-80521/
description: "CVE-2026-80521 (Linux Linux): In the Linux kernel, the following vulnerability has been resolved: afunix: Unlink sccentry in unixdeledge(). Kyle Zeng…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-08-26
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-80521"
kev: false
cvss: 7.8
epss: 0.0017
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Normal patch cycle. No exploitation signal; fix it in your next routine update if you are affected. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.2% , percentile 6: FIRST’s model estimates a 0.2% chance of exploitation activity in the next 30 days, higher than 6% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs local access needed. Lower urgency for most teams unless an attacker could already run code on the machine.
- Editorial verdict: Patch this week. Linux AF_UNIX CVE-2026-80521: Public Container Escape — If you run untrusted or third-party code in containers on a 6.10+ kernel, install fixed kernels as they ship and move that code behind stronger isolation now; a public exploit turns an unprivileged container process into a host compromise.

## What it is

In the Linux kernel, the following vulnerability has been resolved: afunix: Unlink sccentry in unixdeledge(). Kyle Zeng reported that GC could free a dead SCC partially. The scenario is as follows: 1) Create two SCCs: X -. A B ^--' 2) Run the following concurrently: 2-1) send() sk-B to sk-B from sk-X 2-2) close() both A and B At 2-1), there is a small window where unixaddedges() publishes a new edge (B B) to GC but its skb is not queued by skbqueuetail(). If 2-2) completes before skbqueuetail() and GC is triggered, it judges A B as dead, but B is not freed because GC cannot collect the not-yet-queued skb holding the B B edge. X -. A B -. This edge is visible ^--' ^..' but skb is not This itself is not a problem since the next GC run will judge B as dead as well and free it finally. X -. A B -. ^--' ^--' However, X's SCC forces the next GC to call unixwalksccfast(), and it iterates over A through B's sccentry. Let's unlink sccentry before freeing the vertex in unixdeledge().

## Affected products (CVE record)

- Linux Linux: 5dfd283f4651d04dbb70ceb9ae5c4a30eda3c52a < 2b6c2842692d08e7acaf32d1eb47f95def35f3fe, de7921631ff323369aa63a4324695ab54ea4047e < 6fda5c51b8e43a8440f76e65c89d9f95ddb2ef33, 4090fa373f0e763c43610853d2774b5979915959 < 1293fd69a50d188a5788b08ba3741a3e86be1608, 4090fa373f0e763c43610853d2774b5979915959 < fe198b077864feafd4aa4b33b1a5ce26f50195a2, 4090fa373f0e763c43610853d2774b5979915959 < e3702470ced94fad74d71e2232f022d2eb752a6d, 4090fa373f0e763c43610853d2774b5979915959 < 594d905195024b228c962627ae5ae7c17bd582a4, 6.1.141 < 6.1.189, 6.6.93 < 6.6.158
- Linux Linux: 6.10

## Severity

- Linux CVSS 3.1: 7.8 `CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- FIRST EPSS (model of 2026-10-21): 0.17% probability of exploitation activity in the next 30 days; percentile 6.

## Sources

- [CVE.org record CVE-2026-80521](https://www.cve.org/CVERecord?id=CVE-2026-80521)
- [NVD entry CVE-2026-80521](https://nvd.nist.gov/vuln/detail/CVE-2026-80521)
- [git.kernel.org](https://git.kernel.org/stable/c/2b6c2842692d08e7acaf32d1eb47f95def35f3fe)
- [git.kernel.org](https://git.kernel.org/stable/c/6fda5c51b8e43a8440f76e65c89d9f95ddb2ef33)
- [git.kernel.org](https://git.kernel.org/stable/c/1293fd69a50d188a5788b08ba3741a3e86be1608)
- [git.kernel.org](https://git.kernel.org/stable/c/fe198b077864feafd4aa4b33b1a5ce26f50195a2)
- [git.kernel.org](https://git.kernel.org/stable/c/e3702470ced94fad74d71e2232f022d2eb752a6d)
- [git.kernel.org](https://git.kernel.org/stable/c/594d905195024b228c962627ae5ae7c17bd582a4)

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Source page: https://erroneo.us/security/cve/CVE-2026-80521/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt