CVE-2026-44638: Saitoha Libsixel

Low severity, CVSS 2.5. EPSS: 0.1% chance of exploitation in the next 30 days.

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 products

• Saitoha Libsixel: from 1.0.0, before 1.8.7-r2 (fixed in 1.8.7-r2)

Published 2026-05-14. Last modified 2026-06-17.