CVE-2026-44638

libsixel: NULL pointer dereference

State: Published
Severity: 2.5 Low
Published: May 14, 2026
Updated: May 15, 2026
Reserved: May 7, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	2.5 Low	CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L	GitHub_M

Weaknesses

CWE-476 NULL Pointer Dereference
CWE-690 Unchecked Return Value to NULL Pointer Dereference

Affected Products

Product	Versions
libsixelsaitoha	>= 1.0.0, < 1.8.7-r2Affected

References

https://github.com/saitoha/libsixel/security/advisories/GHSA-wpx3-h5g8-qr3w

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.