CVE-2021-41715: libsixel 1.10.0 is vulnerable to Use after free in libsixel/src/dither.c:379.

This month

HIGH 8.8DOWNGRADE

CVE-2021-41715 is a high-severity flaw (CVSS 8.8) affecting libsixel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

libsixel 1.10.0 is vulnerable to Use after free in libsixel/src/dither.c:379.

Why this priority

High severity
Public exploit reference

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

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.0% (top 37%)
CISA exploited list	No
Weakness	CWE-416
Published	2022-04-08
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: libsixel

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

Am I affected?

Timeline

2022-04-08 15:15 UTCPublished CVE record published
2026-06-17 04:08 UTCUpdated Record last modified

libsixel libsixel DOWNGRADE

Affected: 1.10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.10.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.10.0 (Debian / Ubuntu)

apt-cache madison libsixel sudo apt install libsixel=<VERSION_BEFORE_1.10.0> sudo apt-mark hold libsixel

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

dnf --showduplicates list libsixel sudo dnf downgrade libsixel-<VERSION_BEFORE_1.10.0> sudo dnf versionlock add libsixel

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.

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-2021-41715?

libsixel: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-41715 being exploited?

CVE-2021-41715 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-2021-41715 affect?

CVE-2021-41715 affects libsixel. Severity is high (CVSS 8.8). libsixel 1.10.0 is vulnerable to Use after free in libsixel/src/dither.c:379.

How urgent is CVE-2021-41715?

Priority 52/100. High severity; Public exploit reference

Related CVEs

CVE-2026-44637 HIGH 7.1 UPGRADE libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel
CVE-2026-44636 HIGH 7.4 UPGRADE libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel
CVE-2026-44638 LOW 2.5 UPGRADE libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel
CVE-2026-33023 HIGH 7.8 UPGRADE libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel
CVE-2026-33021 HIGH 7.3 UPGRADE libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel

References

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