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Fencer Vulns
medium 5.5

CVE-2021-45402 json

The check_alu_op() function in kernel/bpf/verifier.c in the Linux kernel through v5.16-rc5 did not properly update bounds while handling th…

published 2022-02-11 4 y ago modified 2026-10-08 31 d ago also EUVD-2021-32174

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits
0
none known

Summary

The check_alu_op() function in kernel/bpf/verifier.c in the Linux kernel through v5.16-rc5 did not properly update bounds while handling the mov32 instruction, which allows local users to obtain potentially sensitive address information, aka a "pointer leak."

Patch / fix

  • linux linux_kernel 5.16
  • linux Debian 14, Debian 13, Debian 12 5.15.15-1

debian advisories DEBIAN-CVE-2021-45402

  • linux-aws-5.13 Ubuntu 20.04 LTS 5.13.0-1019.21~20.04.1
  • linux-gcp-5.13 Ubuntu 20.04 LTS 5.13.0-1021.25~20.04.1
  • linux-hwe-5.13 Ubuntu 20.04 LTS 5.13.0-37.42~20.04.1
  • linux-oem-5.14 Ubuntu 20.04 LTS 5.14.0-1022.24
  • linux-azure-5.13 Ubuntu 20.04 LTS 5.13.0-1021.24~20.04.1
  • linux-oracle-5.13 Ubuntu 20.04 LTS 5.13.0-1025.30~20.04.1

ubuntu advisories UBUNTU-CVE-2021-45402

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-azure SLE Module for Public Cloud 15 SP4, openSUSE Leap 15.4 5.14.21-150400.14.7.1
  • kernel-syms-azure SLE Module for Public Cloud 15 SP4, openSUSE Leap 15.4 5.14.21-150400.14.7.1
  • kernel-source-azure SLE Module for Public Cloud 15 SP4, openSUSE Leap 15.4 5.14.21-150400.14.7.1
  • dtb-aarch64 openSUSE Leap 15.4 5.14.21-150400.24.11.1
  • kernel-64kb SLE Module for Basesystem 15 SP4, openSUSE Leap 15.4 5.14.21-150400.24.11.1
  • kernel-syms SLE Module for Development Tools 15 SP4, openSUSE Leap 15.4 5.14.21-150400.24.11.1
  • kernel-obs-qa openSUSE Leap 15.4 5.14.21-150400.24.11.1
  • kernel-source SLE Module for Development Tools 15 SP4, SLE Module for Basesystem 15 SP4, openSUSE Leap 15.4 5.14.21-150400.24.11.1

suse advisories SUSE-SU-2022:2615-1SUSE-SU-2022:2520-1SUSE-SU-2022:1163-1SUSE-SU-2022:1039-1SUSE-SU-2022:1038-1

  • dtb-aarch64 openSUSE Leap 15.3 5.3.18-150300.59.60.4
  • kernel-64kb openSUSE Leap 15.3 5.3.18-150300.59.60.4
  • kernel-syms openSUSE Leap 15.3 5.3.18-150300.59.60.4
  • kernel-obs-qa openSUSE Leap 15.3 5.3.18-150300.59.60.4
  • kernel-source openSUSE Leap 15.3 5.3.18-150300.59.60.4
  • kernel-default openSUSE Leap 15.3 5.3.18-150300.59.60.4
  • kernel-preempt openSUSE Leap 15.3 5.3.18-150300.59.60.4
  • kernel-kvmsmall openSUSE Leap 15.3 5.3.18-150300.59.60.4

opensuse advisories openSUSE-SU-2022:1039-1

  • kernel CBL-Mariner 2.0 5.15.26.1-1

azure linux advisories AZL-8605

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-2021-45402 updated cvss 4.4

kernel: pointer leak in check_alu_op() of kernel/bpf/verifier.c

  • 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
    affected: workaround, no fix available “Fix deferred”
  • 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
    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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
31 d ago

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • git.kernel.org https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=3cf2b61eb06765e27fec6799292d9fb46d0b7e60 referenced PoC, tagged "exploit" by a source, unverified
  • git.kernel.org https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=b1a7288dedc6caf9023f2676b4f5ed34cf0d4029 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:L/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 2.1 AV:L/AC:L/Au:N/C:P/I:N/A:N

Classification

Weakness
  • CWE-668 Exposure of Resource to Wrong Sphere
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.