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Fencer Vulns
high 7.8

CVE-2021-33200 json

kernel/bpf/verifier.c in the Linux kernel through 5.12.7 enforces incorrect limits for pointer arithmetic operations, aka CID-bb01a1bba579.

published 2021-05-27 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-19913

cvss
7.8
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 31%
public exploits
0
none known

Summary

kernel/bpf/verifier.c in the Linux kernel through 5.12.7 enforces incorrect limits for pointer arithmetic operations, aka CID-bb01a1bba579. This can be abused to perform out-of-bounds reads and writes in kernel memory, leading to local privilege escalation to root. In particular, there is a corner case where the off reg causes a masking direction change, which then results in an incorrect final aux->alu_limit.

Patch / fix

  • linux linux_kernel 5.4.123, 5.10.41, 5.12.8
  • linux Debian 14, Debian 13, Debian 12 5.10.40-1

debian advisories DEBIAN-CVE-2021-33200

  • kernel RHEL 8 4.18.0-348.el8
  • perf RHEL 8 4.18.0-348.el8
  • bpftool RHEL 8 4.18.0-348.el8
  • kernel-core RHEL 8 4.18.0-348.el8
  • kernel-tools RHEL 8 4.18.0-348.el8
  • python3-perf RHEL 8 4.18.0-348.el8
  • kernel-modules RHEL 8 4.18.0-348.el8
  • kernel-zfcpdump RHEL 8 4.18.0-348.el8

red hat advisories RHSA-2021:4356RHSA-2021:4140

  • kernel-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.173.1
  • kernel-syms-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.173.1
  • kernel-source-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.173.1
  • kernel-syms SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-122.201.1
  • kernel-source SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-122.201.1
  • kernel-default SLES for SAP 12 SP5, SLES 12 SP5, SLE Workstation Extension 12 SP5 +2 more 4.12.14-122.201.1
  • kernel-obs-build SLE Software Development Kit 12 SP5 4.12.14-122.201.2
  • kernel-syms SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +6 more 4.12.14-197.99.1

suse advisories SUSE-SU-2024:0975-1SUSE-SU-2024:0925-1SUSE-SU-2021:2427-1SUSE-SU-2021:2422-1SUSE-SU-2021:2421-1SUSE-SU-2021:2208-1

  • kernel-default openSUSE Leap 15.3 4.12.14-197.99.1
  • kernel-vanilla openSUSE Leap 15.3 4.12.14-197.99.1
  • kernel-kvmsmall openSUSE Leap 15.3 4.12.14-197.99.1
  • kernel-zfcpdump openSUSE Leap 15.3 4.12.14-197.99.1
  • kernel-64kb openSUSE Leap 15.3 5.3.18-59.5.2
  • kernel-syms openSUSE Leap 15.3 5.3.18-59.5.1
  • kernel-obs-qa openSUSE Leap 15.3 5.3.18-59.5.1
  • kernel-source openSUSE Leap 15.3 5.3.18-59.5.2

opensuse advisories openSUSE-SU-2021:2427-1openSUSE-SU-2021:1977-1openSUSE-SU-2021:1975-1openSUSE-SU-2021:0947-1openSUSE-SU-2021:0843-1

  • kernel CBL-Mariner 2.0 5.10.78.1-1

azure linux advisories AZL-6563

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 5.12.8.arch1-1
  • linux-zen Arch Linux 5.12.8.zen1-1
  • linux-lts Arch Linux 5.10.41-1
  • linux-hardened Arch Linux 5.12.9.hardened1-1

arch linux advisories AVG-2007AVG-2008AVG-2010AVG-2033

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-2021-33200 updated cvss 7.8

kernel: out-of-bounds reads and writes due to enforcing incorrect limits for pointer arithmetic operations by BPF verifier

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, kernel-alt, python-perf, +9 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-348.el8, kernel-debuginfo-common-aarch64 4.18.0-348.el8, kernel-debuginfo-common-ppc64le 4.18.0-348.el8 Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-348.el8, kernel 4.18.0-348.el8, bpftool 4.18.0-348.el8, kernel-core 4.18.0-348.el8, kernel-tools 4.18.0-348.el8, python3-perf 4.18.0-348.el8, +15 more
    fixed: vendor fix RHSA-2021:4356
  • Red Hat Enterprise Linux Real Time (v. 8) kernel-rt 4.18.0-348.rt7.130.el8, kernel-rt-core 4.18.0-348.rt7.130.el8, kernel-rt-modules 4.18.0-348.rt7.130.el8, kernel-rt-debug-core 4.18.0-348.rt7.130.el8, kernel-rt-debug-modules 4.18.0-348.rt7.130.el8, kernel-rt-modules-extra 4.18.0-348.rt7.130.el8, +2 more Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-348.rt7.130.el8, kernel-rt-kvm 4.18.0-348.rt7.130.el8, kernel-rt-core 4.18.0-348.rt7.130.el8, kernel-rt-modules 4.18.0-348.rt7.130.el8, kernel-rt-debug-kvm 4.18.0-348.rt7.130.el8, kernel-rt-debug-core 4.18.0-348.rt7.130.el8, +4 more
    fixed: vendor fix RHSA-2021:4140
  • Red Hat Enterprise Linux 5 kernel Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 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

0.38% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

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

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.