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Fencer Intel
high 7.8

CVE-2026-80521 json

af_unix: Unlink scc_entry in unix_del_edge().

published 2mo ago modified last mo. also EUVD-2026-66587

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

af_unix: Unlink scc_entry in unix_del_edge().

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 unix_add_edges() publishes a new edge (B <-> B) to GC but its skb is not queued by skb_queue_tail().

If 2-2) completes before skb_queue_tail() 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 unix_walk_scc_fast(), and it iterates over A through B's scc_entry.

Let's unlink scc_entry before freeing the vertex in unix_del_edge().

Patch / fix

  • Linux Linux 6.1.189, 6.6.158, 6.12.111, 6.18.53, 7.1.10, 7.2
  • linux Debian 12 6.1.190-1
  • linux Debian 13 6.12.111-1
  • linux Debian 14 7.1.10-1
  • linux-6.12 Debian 12 6.12.111-1~deb12u1

debian advisories DEBIAN-CVE-2026-80521

  • linux Ubuntu 26.04 LTS 7.0.0-42.42
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1016.17
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1016.18
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1017.17
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-42.42.1
  • linux-oracle Ubuntu 26.04 LTS 7.0.0-1015.16
  • linux-hwe-7.0 Ubuntu 24.04 LTS 7.0.0-42.42~24.04.1
  • linux-oem-7.0 Ubuntu 26.04 LTS 7.0.0-1017.17

ubuntu advisories UBUNTU-CVE-2026-80521

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 10.2 6.12.0-211.65.1.el10_2
  • rv RHEL 10.2 6.12.0-211.65.1.el10_2
  • perf RHEL 10.2 6.12.0-211.65.1.el10_2
  • rtla RHEL 10.2 6.12.0-211.65.1.el10_2
  • libperf RHEL 10.2 6.12.0-211.65.1.el10_2
  • kernel-rt RHEL 10.2 6.12.0-211.65.1.el10_2
  • kernel-64k RHEL 10.2 6.12.0-211.65.1.el10_2
  • kernel-core RHEL 10.2 6.12.0-211.65.1.el10_2

red hat advisories RHSA-2026:81406RHSA-2026:77634

  • kernel-livepatch-SLE16-RT_Update_5 Linux Micro 6.2 14-160000.1.1
  • kernel-livepatch-SLE16-RT_Update_3 Linux Micro 6.2 15-160000.1.1
  • kernel-livepatch-SLE16-RT_Update_2 Linux Micro 6.2 16-160000.1.1
  • kernel-livepatch-SLE16-RT_Update_1 Linux Micro 6.2 18-160000.1.1
  • kernel-livepatch-SLE16-RT_Update_0 Linux Micro 6.2 19-160000.3.4
  • kernel-livepatch-SLE16-RT_Update_12 Linux Micro 6.2 8-160000.1.1
  • kernel-livepatch-SLE16-RT_Update_11 Linux Micro 6.2 10-160000.1.1
  • kernel-livepatch-SLE16-RT_Update_10 Linux Micro 6.2 10-160000.1.1

suse advisories SUSE-SU-2026:24534-1SUSE-SU-2026:24535-1SUSE-SU-2026:24536-1SUSE-SU-2026:24537-1SUSE-SU-2026:24538-1SUSE-SU-2026:24526-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.39.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.39.1

opensuse advisories openSUSE-SU-2026:22091-1

  • kernel AlmaLinux 10 6.12.0-211.65.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.65.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.65.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.65.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.65.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.65.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.65.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.65.1.el10_2

almalinux advisories ALSA-2026:81406

  • kernel Rocky Linux 10 6.12.0-211.65.1.el10_2

rocky linux advisories RLSA-2026:81406

Is CVE-2026-80521 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-80521 updated cvss 7.8

kernel: af_unix: Unlink scc_entry in unix_del_edge()

  • Red Hat Enterprise Linux kernel-modules-internal 6.12.0-211.65.1.el10_2 Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.65.1.el10_2, rv 6.12.0-264.14.1.el10_3, perf 6.12.0-211.65.1.el10_2, perf 6.12.0-264.14.1.el10_3, rtla 6.12.0-211.65.1.el10_2, rtla 6.12.0-264.14.1.el10_3, +20 more
    fixed: vendor fix RHSA-2026:81406
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.109.1.el10_0, perf 6.12.0-55.109.1.el10_0, rtla 6.12.0-55.109.1.el10_0, python3-perf 6.12.0-55.109.1.el10_0, kernel-devel-matched 6.12.0-55.109.1.el10_0, kernel-64k-devel-matched 6.12.0-55.109.1.el10_0, +7 more
    fixed: vendor fix RHSA-2026:77634
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.65.1.el10_2, kernel 6.12.0-264.14.1.el10_3, kernel-64k 6.12.0-211.65.1.el10_2, kernel-64k 6.12.0-264.14.1.el10_3, kernel-core 6.12.0-211.65.1.el10_2, kernel-core 6.12.0-264.14.1.el10_3, +62 more
    fixed: vendor fix RHSA-2026:81406
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.109.1.el10_0, kernel-64k 6.12.0-55.109.1.el10_0, kernel-core 6.12.0-55.109.1.el10_0, kernel-tools 6.12.0-55.109.1.el10_0, kernel-modules 6.12.0-55.109.1.el10_0, kernel-64k-core 6.12.0-55.109.1.el10_0, +27 more
    fixed: vendor fix RHSA-2026:77634
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.65.1.el10_2, libperf 6.12.0-264.14.1.el10_3, kernel-debuginfo-common-s390x 6.12.0-211.65.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-264.14.1.el10_3, kernel-debuginfo-common-x86_64 6.12.0-211.65.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-264.14.1.el10_3, +4 more
    fixed: vendor fix RHSA-2026:81406
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.109.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.109.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.109.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.109.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.109.1.el10_0
    fixed: vendor fix RHSA-2026:77634
  • Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal 6.12.0-211.65.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.65.1.el10_2 Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.65.1.el10_2, kernel-rt 6.12.0-264.14.1.el10_3, kernel-rt-64k 6.12.0-211.65.1.el10_2, kernel-rt-64k 6.12.0-264.14.1.el10_3, kernel-rt-core 6.12.0-211.65.1.el10_2, kernel-rt-core 6.12.0-264.14.1.el10_3, +34 more
    fixed: vendor fix RHSA-2026:81406
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.109.1.el10_0, kernel-rt-64k 6.12.0-55.109.1.el10_0, kernel-rt-core 6.12.0-55.109.1.el10_0, kernel-rt-modules 6.12.0-55.109.1.el10_0, kernel-rt-64k-core 6.12.0-55.109.1.el10_0, kernel-rt-debug-core 6.12.0-55.109.1.el10_0, +14 more
    fixed: vendor fix RHSA-2026:77634
show 3 more
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.65.1.el10_2, kernel-rt 6.12.0-264.14.1.el10_3, kernel-rt-core 6.12.0-211.65.1.el10_2, kernel-rt-core 6.12.0-264.14.1.el10_3, kernel-rt-modules 6.12.0-211.65.1.el10_2, kernel-rt-modules 6.12.0-264.14.1.el10_3, +15 more
    fixed: vendor fix RHSA-2026:81406
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.109.1.el10_0, kernel-rt-kvm 6.12.0-55.109.1.el10_0, kernel-rt-core 6.12.0-55.109.1.el10_0, kernel-rt-modules 6.12.0-55.109.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.109.1.el10_0, kernel-rt-debug-core 6.12.0-55.109.1.el10_0, +6 more
    fixed: vendor fix RHSA-2026:77634
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.