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Fencer Vulns
high 7.8

CVE-2021-38300 json

arch/mips/net/bpf_jit.c in the Linux kernel before 5.4.10 can generate undesirable machine code when transforming unprivileged cBPF program…

published 2021-09-20 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-24755

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

arch/mips/net/bpf_jit.c in the Linux kernel before 5.4.10 can generate undesirable machine code when transforming unprivileged cBPF programs, allowing execution of arbitrary code within the kernel context. This occurs because conditional branches can exceed the 128 KB limit of the MIPS architecture.

Patch / fix

  • linux linux_kernel 4.14.251, 4.19.211, 5.4.153, 5.10.71, 5.14.10
  • linux Debian 14, Debian 13, Debian 12 5.14.6-1

debian advisories DEBIAN-CVE-2021-38300

  • linux-hwe-5.13 Ubuntu 20.04 LTS 5.13.0-23.23~20.04.2
  • linux-fips Ubuntu Pro FIPS-updates 18.04 LTS 4.15.0-1075.84
  • linux-fips Ubuntu Pro FIPS-updates 20.04 LTS 5.4.0-1038.44
  • linux-aws-fips Ubuntu Pro FIPS-updates 18.04 LTS 4.15.0-2059.61
  • linux-aws-fips Ubuntu Pro FIPS-updates 20.04 LTS 5.4.0-1069.73+fips2
  • linux-gcp-fips Ubuntu Pro FIPS-updates 18.04 LTS 4.15.0-2024.26
  • 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 18.04 LTS 4.15.0-2041.45

ubuntu advisories UBUNTU-CVE-2021-38300

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 CBL-Mariner 2.0 5.10.78.1-1

azure linux advisories AZL-6594

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-2021-38300 updated cvss 8.1

kernel: crafting anomalous machine code may lead to arbitrary Kernel code execution

  • 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-alt, python-perf, kernel-kdump, +4 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, +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

0.58% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • git.kernel.org https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=37cb28ec7d3a36a5bace7063a3dba633ab110f8b referenced PoC, tagged "exploit" by a source, unverified

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 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C

Classification

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.