CVE catalog

CVE-2026-33018

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

[CVE catalog]

Severity: High · CVSS 7CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Published: Apr 14, 2026, 9:45:42 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.19% · Oct 25, 2026

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.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	libsixel	sid	`1:1.8.7-r2-1`	fixed
Debian	libsixel	forky	`1:1.8.7-r2-1`	fixed
Debian	libsixel	trixie	`1.10.5-1`	vulnerable
Debian	libsixel	bookworm	`1.10.3-3`	vulnerable
Cpe	libsixel	Not reported	Not reported	vulnerable
Cpe	libsixel	Not reported	`1.8.7-r1`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	libsixel	source	sid	`1:1.8.7-r2-1`	not yet assigned	Not reported	[1136211]
Debian	libsixel	source	forky	`1:1.8.7-r2-1`	not yet assigned	Not reported	[1136211]
Debian	libsixel	source	trixie	`(unfixed)`	not yet assigned	Not reported	[1136211]
Debian	libsixel	source	bookworm	`(unfixed)`	not yet assigned	Not reported	[1136211]
Cpe	libsixel	cpe	Not reported	`1.8.7-r1`	Not reported	Not reported	Not reported

[Debian bug #1136211]

Notes

[trixie] libsixel: Minor issue [bookworm] libsixel: Minor issue

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[libsixel1]Affected
Source package: [libsixel]
Details (2)
- 1.10.3-3 · amd64 · bookworm
  Affected
  nvd · libsixel · debian · bookworm; nvd · libsixel · debian · 12
- 1.10.3-3 · arm64 · bookworm
  Affected
  nvd · libsixel · debian · bookworm; nvd · libsixel · debian · 12
[libsixel-bin]Affected
Source package: [libsixel]
Details (2)
- 1.10.3-3 · amd64 · bookworm
  Affected
  nvd · libsixel · debian · bookworm; nvd · libsixel · debian · 12
- 1.10.3-3 · arm64 · bookworm
  Affected
  nvd · libsixel · debian · bookworm; nvd · libsixel · debian · 12
[libsixel-dev]Affected
Source package: [libsixel]
Details (2)
- 1.10.3-3 · amd64 · bookworm
  Affected
  nvd · libsixel · debian · bookworm; nvd · libsixel · debian · 12
- 1.10.3-3 · arm64 · bookworm
  Affected
  nvd · libsixel · debian · bookworm; nvd · libsixel · debian · 12
[libsixel-examples]Affected
Source package: [libsixel]
Details (2)
- 1.10.3-3 · all · bookworm
  Affected
  nvd · libsixel · debian · bookworm; nvd · libsixel · debian · 12
- 1.10.3-3 · all · bookworm
  Affected
  nvd · libsixel · debian · bookworm; nvd · libsixel · debian · 12

[Debian 13 (Trixie)]

[libsixel1]Affected
Source package: [libsixel]
Details (2)
- 1.10.5-1 · amd64 · trixie
  Affected
  nvd · libsixel · debian · 13
- 1.10.5-1 · arm64 · trixie
  Affected
  nvd · libsixel · debian · 13
[libsixel-bin]Affected
Source package: [libsixel]
Details (2)
- 1.10.5-1 · amd64 · trixie
  Affected
  nvd · libsixel · debian · 13
- 1.10.5-1 · arm64 · trixie
  Affected
  nvd · libsixel · debian · 13
[libsixel-dev]Affected
Source package: [libsixel]
Details (2)
- 1.10.5-1 · amd64 · trixie
  Affected
  nvd · libsixel · debian · 13
- 1.10.5-1 · arm64 · trixie
  Affected
  nvd · libsixel · debian · 13
[libsixel-examples]Affected
Source package: [libsixel]
Details (2)
- 1.10.5-1 · all · trixie
  Affected
  nvd · libsixel · debian · 13
- 1.10.5-1 · all · trixie
  Affected
  nvd · libsixel · debian · 13

Observed: Oct 23, 2026, 10:34:17 PM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX]