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Fencer Vulns
high 8.8

CVE-2021-47388 json

mac80211: fix use-after-free in CCMP/GCMP RX

published 2024-05-21 2 y ago modified 2026-08-05 3 mo ago also EUVD-2021-34393

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits
0
none known

Summary

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

mac80211: fix use-after-free in CCMP/GCMP RX

When PN checking is done in mac80211, for fragmentation we need to copy the PN to the RX struct so we can later use it to do a comparison, since commit bf30ca922a0c ("mac80211: check defrag PN against current frame").

Unfortunately, in that commit I used the 'hdr' variable without it being necessarily valid, so use-after-free could occur if it was necessary to reallocate (parts of) the frame.

Fix this by reloading the variable after the code that results in the reallocations, if any.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=214401.

Patch / fix

  • Linux Linux 4.4.286, 4.9.285, 4.14.249, 4.19.209, 5.4.151, 5.10.71, 5.13, 5.14.10, 5.15
  • linux Debian 14, Debian 13, Debian 12 5.14.12-1

debian advisories DEBIAN-CVE-2021-47388

  • linux Ubuntu 18.04 LTS 4.15.0-163.171
  • linux Ubuntu 20.04 LTS 5.4.0-91.102
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1116.123
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1060.63
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1058.62
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1008.9
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1103.105
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1050.52

ubuntu advisories UBUNTU-CVE-2021-47388

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-syms SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-122.225.1
  • kernel-source SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-122.225.1
  • kernel-default SLES for SAP 12 SP5, SLES 12 SP5, SLE Workstation Extension 12 SP5 +2 more 4.12.14-122.225.1
  • kernel-obs-build SLE Software Development Kit 12 SP5 4.12.14-122.225.1
  • kernel-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.194.1
  • kernel-syms-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.194.1
  • kernel-source-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.194.1
  • kernel-rt SLE Real Time 12 SP5 4.12.14-10.197.1

suse advisories SUSE-SU-2024:2940-1SUSE-SU-2024:2901-1SUSE-SU-2024:2892-1SUSE-SU-2024:2190-1SUSE-SU-2024:2189-1SUSE-SU-2024:2185-1

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-2021-47388 updated cvss 6.4

kernel: mac80211: fix use-after-free in CCMP/GCMP RX

  • 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
    affected: workaround, no fix planned “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.”
  • 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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 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

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.