CVE-2026-44638: libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel

Routine

LOW 2.5UPGRADE

CVE-2026-44638 is a low-severity flaw (CVSS 2.5) affecting libsixel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From to 1.8.7-r1, a wrong NULL check after an allocation call in sixel_decode_raw and sixel_decode causes a NULL pointer dereference whenever the allocation fails. The check tests the address of the output parameter (always non-NULL) instead of the value the malloc returned. On allocation failure, the function continues and writes through a NULL pointer, crashing the

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	2.5 (Low)
Attack vector	Local
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.1% (top 97%)
CISA exploited list	No
Weakness	CWE-476, CWE-690
Published	2026-05-14
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: saitoha

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-14 20:17 UTCPublished CVE record published
2026-10-26 14:10 UTCUpdated Record last modified

saitoha libsixel UPGRADE

Affected: >= 1.0.0 and < 1.8.7-r2

Fixed in: 1.8.7-r2

Safe to downgrade to: a release before 1.0.0

1. Check installed version

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

2. UPGRADE to 1.8.7-r2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libsixel

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libsixel

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.0.0 (Debian / Ubuntu)

apt-cache madison libsixel sudo apt install libsixel=<VERSION_BEFORE_1.0.0> sudo apt-mark hold libsixel

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list libsixel sudo dnf downgrade libsixel-<VERSION_BEFORE_1.0.0> 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-2026-44638?

libsixel: upgrade to 1.8.7-r2. Exact commands for each OS are on this page.

Is CVE-2026-44638 being exploited?

CVE-2026-44638 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-2026-44638 affect?

CVE-2026-44638 affects libsixel. Severity is low (CVSS 2.5). libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From to 1.8.7-r1, a wrong NULL check after an allocation call in sixel_decode_raw and sixel_decode causes a NULL pointer dereference whenever the allocation fai

How urgent is CVE-2026-44638?

Priority 14/100. 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

References

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