CVE-2021-45911: An issue was discovered in gif2apng 1.9

This month

HIGH 7.8WATCHLISTDOWNGRADEMITIGATE

CVE-2021-45911 is a high-severity flaw (CVSS 7.8) affecting gif2apng, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in gif2apng 1.9. There is a heap-based buffer overflow in the main function. It allows an attacker to write 2 bytes outside the boundaries of the buffer.

Why this priority

High severity
Public exploit reference
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 40%)
CISA exploited list	No
Weakness	CWE-787
Published	2021-12-28
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · gif2apng project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-12-28 01:15 UTCPublished CVE record published
2026-06-17 04:14 UTCUpdated Record last modified

gif2apng project gif2apng DOWNGRADE

Affected: 1.9

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.9

1. Check installed version

apt-cache policy gif2apng || rpm -q gif2apng || gif2apng --version

2. No fixed release: DOWNGRADE to a release before 1.9 (Debian / Ubuntu)

apt-cache madison gif2apng sudo apt install gif2apng=<VERSION_BEFORE_1.9> sudo apt-mark hold gif2apng

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list gif2apng sudo dnf downgrade gif2apng-<VERSION_BEFORE_1.9> sudo dnf versionlock add gif2apng

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

debian debian linux MITIGATE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-45911?

gif2apng: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-45911 being exploited?

CVE-2021-45911 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-45911 affect?

CVE-2021-45911 affects gif2apng, debian linux. Severity is high (CVSS 7.8). An issue was discovered in gif2apng 1.9. There is a heap-based buffer overflow in the main function. It allows an attacker to write 2 bytes outside the boundaries of the buffer.

How urgent is CVE-2021-45911?

Priority 52/100. High severity; Public exploit reference; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2021-45910 HIGH 7.8 DOWNGRADE MITIGATE An issue was discovered in gif2apng 1.9
CVE-2021-45909 HIGH 7.8 DOWNGRADE MITIGATE An issue was discovered in gif2apng 1.9
CVE-2021-45908 HIGH 7.8 DOWNGRADE An issue was discovered in gif2apng 1.9
CVE-2021-45907 HIGH 7.8 DOWNGRADE An issue was discovered in gif2apng 1.9

References

← Back to latest CVEs