PT-2026-41033 · Saitoha · Libsixel
Published
2026-05-14
·
Updated
2026-05-14
·
CVE-2026-44637
CVSS v3.1
7.1
High
| Vector | AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H |
libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From to 1.8.7-r1, a signed integer overflow in the SIXEL parser's image-buffer doubling loop can lead to an out-of-bounds heap write in sixel decode raw impl. context->pos x grows by repeat count on every sixel character with no upper bound check. Once pos x approaches INT MAX, the expression "pos x + repeat count" used to size the image buffer overflows signed int. Depending on how the overflow wraps, the resize check that should reject oversized buffers can be bypassed, after which a subsequent write computes a large attacker-influenced offset into image->data and writes past the allocation. Reachable from any caller that decodes attacker-supplied SIXEL data, including img2sixel. This vulnerability is fixed in 1.8.7-r2.
Fix
Memory Corruption
Integer Overflow
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Related Identifiers
Affected Products
Libsixel