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Fencer Vulns
medium 6.6

CVE-2021-22600 kev in the critical feed json

Double Free in net/packet/af_packet.c leading to priviledge escalation

published 2022-01-26 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-9736

cvss
6.6
version 3.1, CNA
cisa kev
Exploited
added 2022-04-11
epss
6.6%
EPSS 6.6% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known

Summary

A double free bug in packet_set_ring() in net/packet/af_packet.c can be exploited by a local user through crafted syscalls to escalate privileges or deny service. We recommend upgrading kernel past the effected versions or rebuilding past ec6af094ea28f0f2dda1a6a33b14cd57e36a9755

Patch / fix

cisa required action Apply updates per vendor instructions.

  • Linux Kernel Kernel 5.4.168, 5.10.88, 5.15.11, 5.16-rc6
  • linux Debian 14, Debian 13, Debian 12 5.15.15-1

debian advisories DEBIAN-CVE-2021-22600

  • linux Ubuntu 18.04 LTS 4.15.0-169.177
  • linux Ubuntu 20.04 LTS 5.4.0-100.113
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1121.129
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1066.69
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1065.69
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1061.64
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1015.16
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1107.109

ubuntu advisories UBUNTU-CVE-2021-22600

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-rt SLE Micro 5.0, Real Time Module 15 SP2 5.3.18-73.1
  • kernel-syms-rt Real Time Module 15 SP2 5.3.18-73.1
  • kernel-rt_debug Real Time Module 15 SP2 5.3.18-73.1
  • kernel-source-rt Real Time Module 15 SP2 5.3.18-73.1
  • kernel-rt SLE Micro 5.1, Real Time Module 15 SP3 5.3.18-150300.76.1
  • kernel-syms-rt Real Time Module 15 SP3 5.3.18-150300.76.1
  • kernel-rt_debug Real Time Module 15 SP3 5.3.18-150300.76.1
  • kernel-source-rt Real Time Module 15 SP3 5.3.18-150300.76.1

suse advisories SUSE-SU-2022:0660-1SUSE-SU-2022:0619-1SUSE-SU-2022:0544-1SUSE-SU-2022:0543-1SUSE-SU-2022:0370-1SUSE-SU-2022:0365-1

  • dtb-aarch64 openSUSE Leap 15.3 5.3.18-150300.59.49.1
  • kernel-64kb openSUSE Leap 15.3 5.3.18-150300.59.49.1
  • kernel-syms openSUSE Leap 15.3 5.3.18-150300.59.49.1
  • kernel-obs-qa openSUSE Leap 15.3 5.3.18-150300.59.49.1
  • kernel-source openSUSE Leap 15.3 5.3.18-150300.59.49.1
  • kernel-default openSUSE Leap 15.3 5.3.18-150300.59.49.1
  • kernel-preempt openSUSE Leap 15.3 5.3.18-150300.59.49.1
  • kernel-kvmsmall openSUSE Leap 15.3 5.3.18-150300.59.49.1

opensuse advisories openSUSE-SU-2022:0370-1openSUSE-SU-2022:0363-1

  • kernel CBL-Mariner 2.0 5.15.18.1-1

azure linux advisories AZL-8450

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-2021-22600 updated cvss 7.0

kernel: double free in packet_set_ring() in net/packet/af_packet.c

  • 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, +82 more
    not affected: vulnerable code not present “Only users with access to the AF_PACKET socket can trigger this vulnerability. The mitigation would be to disable CAP_NET_RAW capability for the users that prevents access to AF_PACKET.”

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

Timeline

  1. Published
  2. 0-day patched (Project Zero)
  3. Added to CISA KEV
  4. CISA patch deadline
  5. CISA SSVC: exploitation active

Known exploited

Added
4 y ago
Patch by
2022-05-02 (4 y ago)
Ransomware
Not known
Required action
Apply updates per vendor instructions.
Vendor, product
Linux, Kernel
CISA name
Linux Kernel Privilege Escalation Vulnerability

Zero-day

Detected in real attacks while still unknown to the vendor and the public, per Google Project Zero's 0day In-the-Wild tracker.

Patched
2022-03-07
Details
project zero tracker

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
no
Technical impact
partial
Assessed
21 mo ago

Exploit prediction

6.59% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.6 CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:H
NVD 3.1 7.0 CVSS:3.1/AV:L/AC:H/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

Affected products

  • Linux Kernel Kernel

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.