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Fencer Vulns
medium 5.5

CVE-2021-45868 json

In the Linux kernel before 5.15.3, fs/quota/quota_tree.c does not validate the block number in the quota tree (on disk).

published 2022-03-18 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-32584

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 71%
public exploits
0
none known

Summary

In the Linux kernel before 5.15.3, fs/quota/quota_tree.c does not validate the block number in the quota tree (on disk). This can, for example, lead to a kernel/locking/rwsem.c use-after-free if there is a corrupted quota file.

Patch / fix

  • linux linux_kernel 5.15.3
  • linux Debian 14, Debian 13, Debian 12 5.15.3-1

debian advisories DEBIAN-CVE-2021-45868

  • linux Ubuntu 18.04 LTS 4.15.0-167.175
  • linux Ubuntu 20.04 LTS 5.4.0-97.110
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1119.127
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1064.67
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1063.67
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1061.64
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1013.14
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1106.108

ubuntu advisories UBUNTU-CVE-2021-45868

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 5.2, SLE Micro 5.1, Real Time Module 15 SP3 5.3.18-150300.85.1
  • kernel-syms-rt Real Time Module 15 SP3 5.3.18-150300.85.1
  • kernel-rt_debug Real Time Module 15 SP3 5.3.18-150300.85.1
  • kernel-source-rt Real Time Module 15 SP3 5.3.18-150300.85.1
  • kernel-rt SLE Real Time 12 SP5 4.12.14-10.84.1
  • kernel-syms-rt SLE Real Time 12 SP5 4.12.14-10.84.1
  • kernel-rt_debug SLE Real Time 12 SP5 4.12.14-10.84.1
  • kernel-source-rt SLE Real Time 12 SP5 4.12.14-10.84.1

suse advisories SUSE-SU-2023:0416-1SUSE-SU-2022:1407-1SUSE-SU-2022:1402-1SUSE-SU-2022:1283-1SUSE-SU-2022:1270-1SUSE-SU-2022:1267-1

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-2021-45868 updated cvss 5.1

kernel: fs/quota/quota_tree.c does not validate the block number in the quota tree

  • 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: no fix planned “Will not fix”
  • 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

1.34% chance of exploitation in the next 30 days, higher than 71% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • openwall.com https://www.openwall.com/lists/oss-security/2022/03/17/2 referenced PoC, tagged "exploit" by a source, unverified
  • openwall.com https://www.openwall.com/lists/oss-security/2022/03/17/1 referenced PoC, tagged "exploit" by a source, unverified
  • bugzilla.kernel.org https://bugzilla.kernel.org/show_bug.cgi?id=214655 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P

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.