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Fencer Vulns
high 7.8

CVE-2021-43057 json

An issue was discovered in the Linux kernel before 5.14.8.

published 2021-10-28 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-30010

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

An issue was discovered in the Linux kernel before 5.14.8. A use-after-free in selinux_ptrace_traceme (aka the SELinux handler for PTRACE_TRACEME) could be used by local attackers to cause memory corruption and escalate privileges, aka CID-a3727a8bac0a. This occurs because of an attempt to access the subjective credentials of another task.

Patch / fix

  • linux linux_kernel 5.14.8
  • linux Debian 14, Debian 13, Debian 12 5.14.9-1

debian advisories DEBIAN-CVE-2021-43057

  • linux-hwe-5.13 Ubuntu 20.04 LTS 5.13.0-22.22~20.04.1
  • linux-oem-5.13 Ubuntu 20.04 LTS 5.13.0-1020.24
  • linux-oem-5.14 Ubuntu 20.04 LTS 5.14.0-1005.5

ubuntu advisories UBUNTU-CVE-2021-43057

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 CBL-Mariner 2.0 5.15.2.1-1

azure linux advisories AZL-6602

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2021-43057 updated cvss 7.8

kernel: use-after-free in the SELinux handler for PTRACE_TRACEME

  • 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, kernel-alt, python-perf, +9 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, +82 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

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugs.chromium.org https://bugs.chromium.org/p/project-zero/issues/detail?id=2229 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns 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.