CVE-2021-4156

Exp

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.

Published: 2022-03-23 Last update: 2025-12-11 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-4156 is rated Exploit Available (53.6/100): CVSS High severity, with low exploitation likelihood (EPSS 0.11%). 2 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-4156

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-4156

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-09 0.18% 0.11% -0.07%
2 2026-03-30 0.10% 0.18% +0.08%
3 2025-11-21 — 0.10% —

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-4156

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.1 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 4.2 [email protected]
5.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 4.9 [email protected]

Weakness enumeration for CVE-2021-4156

OS Trackers for CVE-2021-4156

vendor priority summary link
debian not yet assigned CVE-2021-4156 not yet assigned priority: Debian including 1 source packages (libsndfile), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-4156
gentoo normal CVE-2021-4156: 1 GLSA(s) (202309-11), 1 atom(s) (media-libs/libsndfile); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-4156
redhat medium — https://access.redhat.com/security/cve/CVE-2021-4156
suse medium CVE-2021-4156 severity moderate: SUSE including 19 source package names (0.3.32-3.4:libsndfile1-1.0.28-5.15.1, 17:libsndfile1-1.0.28-5.15.1, …), 137 product×package rows across 80 product lines (Container containers/milvus, Container containers/open-webui, … (80 product lines)): Fixed 137. https://www.suse.com/security/cve/CVE-2021-4156/
ubuntu low CVE-2021-4156 low priority: Ubuntu including 1 source packages (libsndfile), 13 status rows across 13 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, trusty, upstream, xenial): released 6, ignored 4, not-affected 3. https://ubuntu.com/security/CVE-2021-4156

Affected software / configurations for CVE-2021-4156

Vendor Product Version Raw CPE
libsndfile_project libsndfile 1.1.10 cpe:2.3:a:libsndfile_project:libsndfile:1.1.10:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2021-4156

cvelogic Threat Intelligence