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Fencer Vulns
medium 6.7

CVE-2021-39656 json

In __configfs_open_file of file.c, there is a possible use-after-free due to improper locking.

published 2021-12-15 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26013

cvss
6.7
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

In __configfs_open_file of file.c, there is a possible use-after-free due to improper locking. This could lead to local escalation of privilege in the kernel with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-174049066References: Upstream kernel

Patch / fix

  • linux Debian 14, Debian 13, Debian 12 5.10.24-1

debian advisories DEBIAN-CVE-2021-39656

  • linux Ubuntu 18.04 LTS 4.15.0-144.148
  • linux Ubuntu 20.04 LTS 5.4.0-73.82
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1103.110
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1048.50
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1043.46
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1043.45
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1092.94
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1039.40

ubuntu advisories UBUNTU-CVE-2021-39656

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

Exploit prediction

0.12% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.7 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 4.6 AV:L/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • n/a Android

Classification

Weakness

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.