CVE-2026-33018
CVE-2026-33018 · libsixel: Use-After-Free in load_gif()
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 a Use-After-Free vulnerability via the load_gif() function in fromgif.c, where a single sixel_frame_t object is reused across all frames of an animated GIF and gif_init_frame() unconditionally frees and reallocates frame->pixels between frames without consulting the object's reference count. Because the public API explicitly provides sixel_frame_ref() to retain a frame and sixel_frame_get_pixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixel_helper_load_image_file() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1.
CVSS 7.0 · High · EPSS 0.2% · Fix available
- Published
- Updated
Stack: system
Affected products and versions
libsixel
- Versions
- < 1.8.7-rc1: Affected
No fix published
libsixel Debian:12
- Versions
- 1.10.3-3
- 1.10.5-1
- 1:1.8.7-1
- 1:1.8.7-2
- 1:1.8.7-3
- 1:1.8.7-4
- 1:1.8.7-5
- 1:1.8.7-6
- 1:1.8.7-r2-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
libsixel Debian:13
- Versions
- 1.10.5-1
- 1:1.8.7-1
- 1:1.8.7-2
- 1:1.8.7-3
- 1:1.8.7-4
- 1:1.8.7-5
- 1:1.8.7-6
- 1:1.8.7-r2-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
libsixel Debian:14
- Versions
- 1.10.5-1
- 1:1.8.7-1
- 1:1.8.7-2
- 1:1.8.7-3
- 1:1.8.7-4
- 1:1.8.7-5
- 1:1.8.7-6
- Affected ranges
- ECOSYSTEM: < 1:1.8.7-r2-1
Update to 1:1.8.7-r2-1
libsixel Ubuntu:16.04:LTS
- Versions
- 1.4.2-1
- 1.5.2-2
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
libsixel Ubuntu:18.04:LTS
- Versions
- 1.5.2-2
- 1.7.3-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
libsixel Ubuntu:20.04:LTS
- Versions
- 1.8.2-1
- 1.8.2-2.1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
libsixel Ubuntu:22.04:LTS
- Versions
- 1.8.6-2
- 1.10.3-2
- 1.10.3-3
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
libsixel Ubuntu:24.04:LTS
- Versions
- 1.10.3-3
- 1.10.3-3build1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
libsixel Ubuntu:25.10
- Versions
- 1.10.5-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
libsixel Ubuntu:26.10
- Versions
- 1.10.5-1build1
- 1:1.8.7-r2-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
libsixel Ubuntu:26.04:LTS
- Versions
- 1.10.5-1
- 1.10.5-1build1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published