CVE catalog

CVE-2026-44637

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-bound

[CVE catalog]

Severity: High · CVSS 7.1CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
Published: May 14, 2026, 8:02:32 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.16% · Oct 25, 2026

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.

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-2026-44637	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]