Skip to content
Fencer Vulns
medium 6.7

CVE-2021-33655 json

When sending malicous data to kernel by ioctl cmd FBIOPUT_VSCREENINFO,kernel will write memory out of bounds.

published 2022-07-18 4 y ago modified 2026-10-14 26 d ago also EUVD-2021-20332

cvss
6.7
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 24%
public exploits
0
none known

Summary

When sending malicous data to kernel by ioctl cmd FBIOPUT_VSCREENINFO,kernel will write memory out of bounds.

Patch / fix

  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem V1.1
  • linux Debian 14, Debian 13, Debian 12 5.18.14-1

debian advisories DEBIAN-CVE-2021-33655

  • linux Ubuntu 18.04 LTS 4.15.0-193.204
  • linux Ubuntu 20.04 LTS 5.4.0-126.142
  • linux Ubuntu 22.04 LTS 5.15.0-48.54
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1141.152
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1085.92
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1020.24
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1089.97
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1018.24

ubuntu advisories UBUNTU-CVE-2021-33655

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 RHEL 9 5.14.0-284.11.1.el9_2
  • perf RHEL 9 5.14.0-284.11.1.el9_2
  • rtla RHEL 9 5.14.0-284.11.1.el9_2
  • bpftool RHEL 9 7.0.0-284.11.1.el9_2
  • kernel-64k RHEL 9 5.14.0-284.11.1.el9_2
  • kernel-core RHEL 9 5.14.0-284.11.1.el9_2
  • kernel-tools RHEL 9 5.14.0-284.11.1.el9_2
  • python3-perf RHEL 9 5.14.0-284.11.1.el9_2

red hat advisories RHSA-2023:2458RHSA-2023:2148RHSA-2024:0930RHSA-2023:2736RHSA-2023:2951

  • kernel-rt SLE Real Time 12 SP5 4.12.14-10.97.1
  • kernel-syms-rt SLE Real Time 12 SP5 4.12.14-10.97.1
  • kernel-rt_debug SLE Real Time 12 SP5 4.12.14-10.97.1
  • kernel-source-rt SLE Real Time 12 SP5 4.12.14-10.97.1
  • kernel-rt SLE Micro 5.2, SLE Micro 5.1, Real Time Module 15 SP3 +1 more 5.3.18-150300.99.1
  • kernel-syms-rt Real Time Module 15 SP3 5.3.18-150300.99.1
  • kernel-rt_debug Real Time Module 15 SP3 5.3.18-150300.99.1
  • kernel-source-rt Real Time Module 15 SP3 5.3.18-150300.99.1

suse advisories SUSE-SU-2023:0416-1SUSE-SU-2022:4129-1SUSE-SU-2022:4113-1SUSE-SU-2022:4100-1SUSE-SU-2022:4112-1SUSE-SU-2022:4035-1

  • kernel-rt AlmaLinux 8 4.18.0-477.10.1.rt7.274.el8_8
  • kernel-rt-kvm AlmaLinux 8 4.18.0-477.10.1.rt7.274.el8_8
  • kernel-rt-core AlmaLinux 8 4.18.0-477.10.1.rt7.274.el8_8
  • kernel-rt-modules AlmaLinux 8 4.18.0-477.10.1.rt7.274.el8_8
  • kernel-rt-debug-kvm AlmaLinux 8 4.18.0-477.10.1.rt7.274.el8_8
  • kernel-rt-debug-core AlmaLinux 8 4.18.0-477.10.1.rt7.274.el8_8
  • kernel-rt-debug-modules AlmaLinux 8 4.18.0-477.10.1.rt7.274.el8_8
  • kernel-rt-modules-extra AlmaLinux 8 4.18.0-477.10.1.rt7.274.el8_8

almalinux advisories ALSA-2023:2736ALSA-2023:2951ALSA-2023:2148ALSA-2023:2458

  • kernel CBL-Mariner 2.0 5.15.67.1-4

azure linux advisories AZL-10616

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-lts Arch Linux 5.15.54-1
  • linux-hardened Arch Linux 5.18.11.hardened1-1
  • linux-zen Arch Linux 5.18.11.zen1-1
  • linux Arch Linux 5.18.11.arch1-1

arch linux advisories AVG-2772AVG-2773AVG-2774AVG-2775

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-2021-33655 updated cvss 6.7

kernel: malicious data for FBIOPUT_VSCREENINFO ioctl may cause OOB write memory

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder EUS (v.8.6) kernel-debuginfo-common-x86_64 4.18.0-372.93.1.el8_6, kernel-debuginfo-common-aarch64 4.18.0-372.93.1.el8_6, kernel-debuginfo-common-ppc64le 4.18.0-372.93.1.el8_6
    fixed: vendor fix RHSA-2024:0930
  • Red Hat Enterprise Linux AppStream (v. 9) perf 5.14.0-284.11.1.el9_2, rtla 5.14.0-284.11.1.el9_2, kernel-devel-matched 5.14.0-284.11.1.el9_2, kernel-64k-devel-matched 5.14.0-284.11.1.el9_2, kernel-debug-devel-matched 5.14.0-284.11.1.el9_2, kernel-debuginfo-common-s390x 5.14.0-284.11.1.el9_2, +5 more
    fixed: vendor fix RHSA-2023:2458
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-477.10.1.el8_8, kernel 4.18.0-477.10.1.el8_8, bpftool 4.18.0-477.10.1.el8_8, kernel-core 4.18.0-477.10.1.el8_8, kernel-tools 4.18.0-477.10.1.el8_8, python3-perf 4.18.0-477.10.1.el8_8, +15 more
    fixed: vendor fix RHSA-2023:2951
  • Red Hat Enterprise Linux BaseOS (v. 9) bpftool 7.0.0-284.11.1.el9_2, kernel 5.14.0-284.11.1.el9_2, kernel-64k 5.14.0-284.11.1.el9_2, kernel-core 5.14.0-284.11.1.el9_2, kernel-tools 5.14.0-284.11.1.el9_2, python3-perf 5.14.0-284.11.1.el9_2, +28 more
    fixed: vendor fix RHSA-2023:2458
  • Red Hat Enterprise Linux BaseOS EUS (v.8.6) perf 4.18.0-372.93.1.el8_6, kernel 4.18.0-372.93.1.el8_6, bpftool 4.18.0-372.93.1.el8_6, kernel-core 4.18.0-372.93.1.el8_6, kernel-tools 4.18.0-372.93.1.el8_6, python3-perf 4.18.0-372.93.1.el8_6, +15 more
    fixed: vendor fix RHSA-2024:0930
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-477.10.1.el8_8, kernel-debuginfo-common-aarch64 4.18.0-477.10.1.el8_8, kernel-debuginfo-common-ppc64le 4.18.0-477.10.1.el8_8
    fixed: vendor fix RHSA-2023:2951
  • Red Hat Enterprise Linux CRB (v. 9) kernel-debuginfo-common-s390x 5.14.0-284.11.1.el9_2, kernel-debuginfo-common-x86_64 5.14.0-284.11.1.el9_2, kernel-debuginfo-common-aarch64 5.14.0-284.11.1.el9_2, kernel-debuginfo-common-ppc64le 5.14.0-284.11.1.el9_2
    fixed: vendor fix RHSA-2023:2458
show 6 more
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-477.10.1.rt7.274.el8_8, kernel-rt-kvm 4.18.0-477.10.1.rt7.274.el8_8, kernel-rt-core 4.18.0-477.10.1.rt7.274.el8_8, kernel-rt-modules 4.18.0-477.10.1.rt7.274.el8_8, kernel-rt-debug-kvm 4.18.0-477.10.1.rt7.274.el8_8, kernel-rt-debug-core 4.18.0-477.10.1.rt7.274.el8_8, +4 more
    fixed: vendor fix RHSA-2023:2736
  • Red Hat Enterprise Linux NFV (v. 9) kernel-rt 5.14.0-284.11.1.rt14.296.el9_2, kernel-rt-kvm 5.14.0-284.11.1.rt14.296.el9_2, kernel-rt-core 5.14.0-284.11.1.rt14.296.el9_2, kernel-rt-modules 5.14.0-284.11.1.rt14.296.el9_2, kernel-rt-debug-kvm 5.14.0-284.11.1.rt14.296.el9_2, kernel-rt-debug-core 5.14.0-284.11.1.rt14.296.el9_2, +6 more
    fixed: vendor fix RHSA-2023:2148
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-477.10.1.rt7.274.el8_8, kernel-rt-core 4.18.0-477.10.1.rt7.274.el8_8, kernel-rt-modules 4.18.0-477.10.1.rt7.274.el8_8, kernel-rt-debug-core 4.18.0-477.10.1.rt7.274.el8_8, kernel-rt-debug-modules 4.18.0-477.10.1.rt7.274.el8_8, kernel-rt-modules-extra 4.18.0-477.10.1.rt7.274.el8_8, +2 more
    fixed: vendor fix RHSA-2023:2736
  • Red Hat Enterprise Linux RT (v. 9) kernel-rt 5.14.0-284.11.1.rt14.296.el9_2, kernel-rt-core 5.14.0-284.11.1.rt14.296.el9_2, kernel-rt-modules 5.14.0-284.11.1.rt14.296.el9_2, kernel-rt-debug-core 5.14.0-284.11.1.rt14.296.el9_2, kernel-rt-modules-core 5.14.0-284.11.1.rt14.296.el9_2, kernel-rt-debug-modules 5.14.0-284.11.1.rt14.296.el9_2, +4 more
    fixed: vendor fix RHSA-2023:2148
  • Red Hat Virtualization 4 Hypervisor for RHEL 8 perf 4.18.0-372.93.1.el8_6, kernel-debuginfo-common-x86_64 4.18.0-372.93.1.el8_6
    fixed: vendor fix RHSA-2024:0930
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 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 ICSA-23-166-11 updated cvss 6.7

Siemens SIMATIC S7-1500 TM MFP Linux Kernel

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 24% 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

Affected products

  • n/a kernel
  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

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.