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Fencer Vulns
medium 5.5

CVE-2020-12771 json

An issue was discovered in the Linux kernel through 5.6.11.

published 2020-05-09 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-5056

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

An issue was discovered in the Linux kernel through 5.6.11. btree_gc_coalesce in drivers/md/bcache/btree.c has a deadlock if a coalescing operation fails.

Patch / fix

  • linux Debian 14, Debian 13, Debian 12 5.7.6-1

debian advisories DEBIAN-CVE-2020-12771

  • linux Ubuntu 16.04 LTS 4.4.0-187.217
  • linux Ubuntu 18.04 LTS 4.15.0-115.116
  • linux Ubuntu 20.04 LTS 5.4.0-45.49
  • linux-aws Ubuntu 16.04 LTS 4.4.0-1112.124
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1080.84
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1022.22
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1081.92~16.04.1
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1022.22

ubuntu advisories UBUNTU-CVE-2020-12771

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 SP1 4.12.14-14.28.1
  • kernel-syms-rt Real Time Module 15 SP1 4.12.14-14.28.1
  • kernel-rt_debug Real Time Module 15 SP1 4.12.14-14.28.1
  • kernel-source-rt Real Time Module 15 SP1 4.12.14-14.28.1
  • kernel-rt SLE Real Time 12 SP5 4.12.14-10.13.1
  • kernel-syms-rt SLE Real Time 12 SP5 4.12.14-10.13.1
  • kernel-rt_debug SLE Real Time 12 SP5 4.12.14-10.13.1
  • kernel-source-rt SLE Real Time 12 SP5 4.12.14-10.13.1

suse advisories SUSE-SU-2020:2487-1SUSE-SU-2020:2478-1SUSE-SU-2020:2152-1SUSE-SU-2020:2134-1SUSE-SU-2020:2122-1SUSE-SU-2020:2121-1

  • 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-syms openSUSE Leap 15.1 4.12.14-lp151.28.59.1
  • kernel-obs-qa openSUSE Leap 15.1 4.12.14-lp151.28.59.1
  • kernel-source openSUSE Leap 15.1 4.12.14-lp151.28.59.1
  • kernel-default openSUSE Leap 15.1 4.12.14-lp151.28.59.1

opensuse advisories openSUSE-SU-2021:0242-1openSUSE-SU-2020:1153-1openSUSE-SU-2020:1062-1

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-2020-12771 updated cvss 5.1

kernel: deadlock if a coalescing operation fails in btree_gc_coalesce function in drivers/md/bcache/btree.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

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • lkml.org https://lkml.org/lkml/2020/4/26/87 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:N/I:N/A:H
NVD 2.0 4.9 AV:L/AC:L/Au:N/C:N/I:N/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.