DEBIAN-CVE-2026-33020
- Source
- https://security-tracker.debian.org/tracker/CVE-2026-33020
- Import Source
- https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33020.json
- JSON Data
- https://api.osv.dev/v1/vulns/DEBIAN-CVE-2026-33020
- Upstream
- Published
- 2026-04-14T22:16:30Z
- Modified
- 2026-09-14T17:03:28Z
- Severity
-
- 7.1 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H CVSS Calculator
- Summary
- [none]
- Details
-
libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain an integer overflow which leads to a heap buffer overflow via sixel_frame_convert_to_rgb888() in frame.c, where allocation size and pointer offset computations for palettised images (PAL1, PAL2, PAL4) are performed using int arithmetic before casting to size_t. For images whose pixel count exceeds INT_MAX / 4, the overflow produces an undersized heap allocation for the conversion buffer and a negative pointer offset for the normalization sub-buffer, after which sixel_helper_normalize_pixelformat() writes the full image data starting from the invalid pointer, causing massive heap corruption confirmed by ASAN. An attacker providing a specially crafted large palettised PNG can corrupt the heap of the victim process, resulting in a reliable crash and potential arbitrary code execution. This issue has been fixed in version 1.8.7-r1.
- References
Affected packages
Debian:12 / libsixel
Package
- Name
- libsixel
- Purl
- pkg:deb/debian/libsixel?arch=source&distro=bookworm
Affected ranges
- Type
- ECOSYSTEM
- Events
-
Introduced0 Unknown introduced version / All previous versions are affected
Debian:13 / libsixel
Package
- Name
- libsixel
- Purl
- pkg:deb/debian/libsixel?arch=source&distro=trixie
Affected ranges
- Type
- ECOSYSTEM
- Events
-
Introduced0 Unknown introduced version / All previous versions are affected
Debian:14 / libsixel
Package
- Name
- libsixel
- Purl
- pkg:deb/debian/libsixel?arch=source&distro=forky