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Fencer Intel
high 7.8

CVE-2021-35039 json

kernel/module.c in the Linux kernel before 5.12.14 mishandles Signature Verification, aka CID-0c18f29aae7c.

published 5y ago modified 4mo ago also EUVD-2021-21686

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 16%
public exploits
0
none known

Summary

kernel/module.c in the Linux kernel before 5.12.14 mishandles Signature Verification, aka CID-0c18f29aae7c. Without CONFIG_MODULE_SIG, verification that a kernel module is signed, for loading via init_module, does not occur for a module.sig_enforce=1 command-line argument.

Patch / fix

  • linux linux_kernel 4.19.196, 5.4.129, 5.10.47, 5.12.14
  • linux Debian 14, Debian 13, Debian 12 5.14.6-1

debian advisories DEBIAN-CVE-2021-35039

  • linux-aws-5.11 Ubuntu 20.04 LTS 5.11.0-1017.18~20.04.1
  • linux-gcp-5.11 Ubuntu 20.04 LTS 5.11.0-1018.20~20.04.2
  • linux-azure-5.11 Ubuntu 20.04 LTS 5.11.0-1015.16~20.04.1
  • linux-oracle-5.11 Ubuntu 20.04 LTS 5.11.0-1017.18~20.04.1
  • linux-fips Ubuntu Pro FIPS-updates 20.04 LTS 5.4.0-1033.38
  • linux-aws-fips Ubuntu Pro FIPS-updates 20.04 LTS 5.4.0-1069.73+fips2
  • linux-gcp-fips Ubuntu Pro FIPS-updates 20.04 LTS 5.4.0-1067.71~20.04.1
  • linux-azure-fips Ubuntu Pro FIPS-updates 20.04 LTS 5.4.0-1073.76+fips1

ubuntu advisories UBUNTU-CVE-2021-35039

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-64kb SLE Module for Basesystem 15 SP3 5.3.18-59.19.1
  • kernel-syms SLE Module for Development Tools 15 SP3 5.3.18-59.19.1
  • kernel-source SLE Module for Development Tools 15 SP3, SLE Module for Basesystem 15 SP3 5.3.18-59.19.1
  • kernel-default SLE Workstation Extension 15 SP3, SLE Module for Legacy 15 SP3, SLE Module for Basesystem 15 SP3 +2 more 5.3.18-59.19.1
  • kernel-preempt SLE Workstation Extension 15 SP3, SLE Module for Development Tools 15 SP3, SLE Module for Basesystem 15 SP3 5.3.18-59.19.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP3 5.3.18-59.19.1
  • kernel-obs-build SLE Module for Development Tools 15 SP3 5.3.18-59.19.1
  • kernel-default-base SLE Module for Basesystem 15 SP3 5.3.18-59.19.1.18.10.1

suse advisories SUSE-SU-2021:2687-1SUSE-SU-2021:2645-1SUSE-SU-2021:2599-2SUSE-SU-2021:2599-1SUSE-SU-2021:2438-1SUSE-SU-2021:2408-1

  • dtb-aarch64 openSUSE Leap 15.3 5.3.18-59.19.1
  • kernel-64kb openSUSE Leap 15.3 5.3.18-59.19.1
  • kernel-syms openSUSE Leap 15.3 5.3.18-59.19.1
  • kernel-obs-qa openSUSE Leap 15.3 5.3.18-59.19.1
  • kernel-source openSUSE Leap 15.3 5.3.18-59.19.1
  • kernel-default openSUSE Leap 15.3 5.3.18-59.19.1
  • kernel-preempt openSUSE Leap 15.3 5.3.18-59.19.1
  • kernel-kvmsmall openSUSE Leap 15.3 5.3.18-59.19.1

opensuse advisories openSUSE-SU-2021:2687-1openSUSE-SU-2021:2645-1openSUSE-SU-2021:1076-1

  • kernel CBL-Mariner 2.0 5.10.78.1-1

azure linux advisories AZL-6570

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

  • linux Arch Linux 5.12.14.arch1-1
  • linux-zen Arch Linux 5.12.14.zen1-1
  • linux-hardened Arch Linux 5.12.14.hardened1-1
  • linux-lts Arch Linux 5.10.47-1

arch linux advisories AVG-2119AVG-2120AVG-2121AVG-2122

Is CVE-2021-35039 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2021-35039 updated cvss 7.8

kernel: allows loading unsigned kernel modules via init_module syscall

  • 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

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-09).

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 6.9 AV:L/AC:M/Au:N/C:C/I:C/A:C

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature
Technology feeds

References

Sources

Fencer Intel 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.