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Fencer Vulns
high 7.1

CVE-2021-4156 json

An out-of-bounds read flaw was found in libsndfile's FLAC codec functionality.

published 2022-03-23 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-34024

cvss
7.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

An out-of-bounds read flaw was found in libsndfile's FLAC codec functionality. An attacker who is able to submit a specially crafted file (via tricking a user to open or otherwise) to an application linked with libsndfile and using the FLAC codec, could trigger an out-of-bounds read that would most likely cause a crash but could potentially leak memory information that could be used in further exploitation of other flaws.

Patch / fix

  • libsndfile Debian 14, Debian 13, Debian 12 1.1.0-1

debian advisories DEBIAN-CVE-2021-4156

  • libsndfile Ubuntu 20.04 LTS 1.0.28-7ubuntu0.3
  • libsndfile Ubuntu 22.04 LTS 1.0.31-2ubuntu0.2
  • libsndfile Ubuntu Pro 14.04 LTS 1.0.25-7ubuntu2.2+esm4
  • libsndfile Ubuntu Pro 16.04 LTS 1.0.25-10ubuntu0.16.04.3+esm2
  • libsndfile Ubuntu Pro 18.04 LTS 1.0.28-4ubuntu0.18.04.2+esm2

ubuntu advisories UBUNTU-CVE-2021-4156

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

  • libsndfile RHEL 8 1.0.28-12.el8

red hat advisories RHSA-2022:1968

  • libsndfile SLES 15 SP2-BCL, SLES 15 SP1-BCL, SLE Real Time 15 SP2 +19 more 1.0.28-5.15.1
  • libsndfile SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +11 more 1.0.25-36.26.1
  • libsndfile SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 1.0.20-2.19.18.1

suse advisories SUSE-SU-2022:0052-2SUSE-SU-2022:0052-1SUSE-SU-2022:0034-1SUSE-SU-2022:14872-1

  • libsndfile openSUSE Tumbleweed 1.0.31-3.1
  • libsndfile openSUSE Leap 15.3 1.0.28-5.15.1
  • libsndfile-progs openSUSE Leap 15.3 1.0.28-5.15.1

opensuse advisories openSUSE-SU-2024:11705-1openSUSE-SU-2022:0052-1

  • libsndfile AlmaLinux 8 1.0.28-12.el8

almalinux advisories ALSA-2022:1968

  • libsndfile Rocky Linux 8 1.0.28-12.el8

rocky linux advisories RLSA-2022:1968

  • libsndfile Arch Linux 1.1.0-1
  • lib32-libsndfile Arch Linux 1.1.0-1

arch linux advisories AVG-2704AVG-2705

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-2021-4156 updated cvss 7.1

libsndfile: heap out-of-bounds read in src/flac.c in flac_buffer_copy

  • Red Hat Enterprise Linux 6 libsndfile Red Hat Enterprise Linux 7 libsndfile, libsndfile-utils
    affected: workaround, no fix planned “One way to mitigate the risk of this flaw is to not open untrusted sound files using libsndfile or other linked programs.”
  • Red Hat Enterprise Linux AppStream (v. 8) libsndfile 1.0.28-12.el8 Red Hat Enterprise Linux CRB (v. 8) libsndfile-devel 1.0.28-12.el8, libsndfile-debuginfo 1.0.28-12.el8, libsndfile-debugsource 1.0.28-12.el8, libsndfile-utils-debuginfo 1.0.28-12.el8
    fixed: vendor fix “One way to mitigate the risk of this flaw is to not open untrusted sound files using libsndfile or other linked programs.” RHSA-2022:1968
  • Red Hat Enterprise Linux 9 libsndfile, libsndfile-utils
    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

1.75% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=2027690 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/libsndfile/libsndfile/issues/731 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H
NVD 2.0 5.8 AV:N/AC:M/Au:N/C:P/I:N/A:P

Affected products

  • n/a libsndfile

Classification

Weakness

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.