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Fencer Vulns
medium 5.5

CVE-2020-28941 json

An issue was discovered in drivers/accessibility/speakup/spk_ttyio.c in the Linux kernel through 5.9.9.

published 2020-11-19 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-21329

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits
0
none known

Summary

An issue was discovered in drivers/accessibility/speakup/spk_ttyio.c in the Linux kernel through 5.9.9. Local attackers on systems with the speakup driver could cause a local denial of service attack, aka CID-d41227544427. This occurs because of an invalid free when the line discipline is used more than once.

Patch / fix

  • linux Debian 14, Debian 13, Debian 12 5.9.11-1

debian advisories DEBIAN-CVE-2020-28941

  • linux Ubuntu 18.04 LTS 4.15.0-136.140
  • linux Ubuntu 20.04 LTS 5.4.0-66.74
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1094.101
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1038.40
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1093.106~16.04.1
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1037.40
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1036.38
  • linux-hwe Ubuntu 16.04 LTS 4.15.0-136.140~16.04.1

ubuntu advisories UBUNTU-CVE-2020-28941

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-rt Real Time Module 15 SP2 5.3.18-19.1
  • kernel-syms-rt Real Time Module 15 SP2 5.3.18-19.1
  • kernel-rt_debug Real Time Module 15 SP2 5.3.18-19.1
  • kernel-source-rt Real Time Module 15 SP2 5.3.18-19.1
  • kernel-syms SLE Module for Development Tools 15 SP2 5.3.18-24.43.2
  • kernel-source SLE Module for Development Tools 15 SP2, SLE Module for Basesystem 15 SP2 5.3.18-24.43.2
  • kernel-default SLE Workstation Extension 15 SP2, SLE Module for Legacy 15 SP2, SLE Module for Basesystem 15 SP2 +2 more 5.3.18-24.43.2
  • kernel-preempt SLE Module for Development Tools 15 SP2, SLE Module for Basesystem 15 SP2 5.3.18-24.43.2

suse advisories SUSE-SU-2020:3764-1SUSE-SU-2020:3748-1SUSE-SU-2020:3713-1

  • kernel-rt openSUSE Leap 15.2 5.3.18-lp152.3.5.1
  • kernel-syms-rt openSUSE Leap 15.2 5.3.18-lp152.3.5.1
  • kernel-rt_debug openSUSE Leap 15.2 5.3.18-lp152.3.5.1
  • kernel-source-rt openSUSE Leap 15.2 5.3.18-lp152.3.5.1
  • kernel-default-base openSUSE Leap 15.2 5.3.18-lp152.57.1.lp152.8.17.1
  • kernel-syms openSUSE Leap 15.2 5.3.18-lp152.54.1
  • kernel-obs-qa openSUSE Leap 15.2 5.3.18-lp152.54.1
  • kernel-source openSUSE Leap 15.2 5.3.18-lp152.54.1

opensuse advisories openSUSE-SU-2021:0242-1openSUSE-SU-2020:2260-1openSUSE-SU-2020:2161-1

  • linux Arch Linux 5.9.11.arch1-1

arch linux advisories AVG-1284

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-2020-28941 updated cvss 0.0

kernel: NULL pointer dereference in spk_ttyio_ldisc_close function in drivers/accessibility/speakup/spk_ttyio.c

  • 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 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 MRG 2 kernel-rt, mrg-rt-release, kernel-rt-trace, kernel-rt-vanilla, kernel-rt-firmware
    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
5 mo ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.9 AV:L/AC:L/Au:N/C:N/I:N/A:C

Classification

Weakness
  • CWE-763 Release of Invalid Pointer or Reference
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.