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Vulnerability · Published May 14, 2026 · Assigned by GitHub_M

CVE-2026-44638libsixel: NULL pointer dereference

Low 2.5

In plain English

A low-severity null pointer dereference in libsixel from saitoha. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)2.5Low
Exploit odds (30 days)0.1%top 97.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

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 process. This is a denial of service against any caller of these public APIs that hits a low-memory condition. This vulnerability is fixed in 1.8.7-r2.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12libsixelno fix listedDEBIAN-CVE-2026-44638
Debian:13libsixelno fix listedDEBIAN-CVE-2026-44638
Debian:14libsixel1:1.8.7-r2-1DEBIAN-CVE-2026-44638
Ubuntu:22.04:LTSlibsixelno fix listedUBUNTU-CVE-2026-44638
Ubuntu:24.04:LTSlibsixelno fix listedUBUNTU-CVE-2026-44638
Ubuntu:25.10libsixelno fix listedUBUNTU-CVE-2026-44638
Ubuntu:26.04:LTSlibsixelno fix listedUBUNTU-CVE-2026-44638
Ubuntu:26.10libsixelno fix listedUBUNTU-CVE-2026-44638

Affected products (as reported)

VendorProductVersions
saitoha libsixel >= 1.0.0, < 1.8.7-r2

Weakness: CWE-476, CWE-690 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L

References