An issue was discovered in gif2apng 1.9.

published 2021-12-28 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-32624

cvss: 7.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits: 0; none known

An issue was discovered in gif2apng 1.9. There is a heap-based buffer overflow vulnerability in the DecodeLZW function. It allows an attacker to write a large amount of arbitrary data outside the boundaries of a buffer.

Patch / fix

distros 2

debian ubuntu

gif2apng Debian 11 1.9+srconly-3+deb11u1

debian advisories DEBIAN-CVE-2021-45909

gif2apng Ubuntu 18.04 LTS 1.9+srconly-2ubuntu0.1
gif2apng Ubuntu 20.04 LTS 1.9+srconly-3ubuntu0.1
gif2apng Ubuntu Pro 16.04 LTS 1.7-3ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2021-45909

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

Exploit prediction

0.90% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

bugs.debian.org https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1002668 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD	2.0	6.8	AV:N/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness

CWE-787 Out-of-bounds Write

References

bugs.debian.org /cgi-bin/bugreport.cgi?bug=1002668
exploit, issue-tracking, mailing-list, third-party-advisory
lists.debian.org /debian-lts-announce/2022/03/msg00008.html
mailing-list, third-party-advisory

Sources

CVE List CVE-2021-45909
NVD CVE-2021-45909

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.

Summary