CVE catalog

CVE-2026-44636

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From to 1.8.7-r1, signed integer overflow in sixel_encode_highcolor's allocation size calculation can lead to a heap buf

[CVE catalog]

Severity: High · CVSS 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published: May 14, 2026, 8:01:27 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.10% · Oct 25, 2026

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From to 1.8.7-r1, signed integer overflow in sixel_encode_highcolor's allocation size calculation can lead to a heap buffer overflow. The public sixel_encode entry point validates only that width and height are greater than zero, with no upper bound. width and height are multiplied as plain int when computing the allocation size for paletted_pixels and normalized_pixels. Any caller that asks libsixel to encode a pixel buffer with width times height greater than INT_MAX (about 2.15 billion) will hit a wrapped allocation size; under the right wrap, the malloc succeeds with a buffer much smaller than the encoder expects, and the encoder writes past the end of the heap allocation. This vulnerability is fixed in 1.8.7-r2.

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-r2`	fixed
Cpe	libsixel	Not reported	`1.8.7-r2`	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	Not reported
Debian	libsixel	source	forky	`1:1.8.7-r2-1`	not yet assigned	Not reported	Not reported
Debian	libsixel	source	trixie	`(unfixed)`	not yet assigned	Not reported	Not reported
Debian	libsixel	source	bookworm	`(unfixed)`	not yet assigned	Not reported	Not reported
Cpe	libsixel	cpe	Not reported	`1.8.7-r2`	Not reported	Not reported	Not reported
Cpe	libsixel	cpe	Not reported	`1.8.7-r2`	Not reported	NVD-CVE-2026-44636	Not reported

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 26, 2026, 2:25:15 PM UTC

References

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