CVE-2026-33019

CVE-2026-33019 · libsixel: Integer overflow leads to Out-of-bounds Read in img2sixel

This page contains facts from public vulnerability sources. Check the original advisory before updating.

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain an integer overflow leading to an out-of-bounds heap read in the --crop option handling of img2sixel, where positive coordinates up to INT_MAX are accepted without overflow-safe bounds checking. In sixel_encoder_do_clip(), the expression clip_w + clip_x overflows to a large negative value when clip_x is INT_MAX, causing the bounds guard to be skipped entirely, and the unclamped coordinate is passed through sixel_frame_clip() to clip(), which computes a source pointer far beyond the image buffer and passes it to memmove(). An attacker supplying a specially crafted crop argument with any valid image can trigger an out-of-bounds read in the heap, resulting in a reliable crash and potential information disclosure. This issue has been fixed in version 1.8.7-r1.

CVSS 7.1 · High · EPSS 0.3% · Fix available

Published

2026-04-14T21:49:25.204Z

Updated

2026-04-15T20:02:46.628Z

Stack: system

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