PT-2026-32926 · Libsixel · Libsixel

Nicoppida · Published 2026-04-14 · Updated 2026-04-15 · CVE-2026-33019

Positive Technologies (AI Summary)

CVSS v3.1

7.1

High

Base vector

AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

Name of the Vulnerable Software and Affected Versions libsixel versions prior to 1.8.7-r1

Description An integer overflow exists in the handling of the '--crop' option in img2sixel. When positive coordinates up to INT MAX are provided, the sixel encoder do clip() function fails to perform overflow-safe bounds checking. Specifically, the expression clip w + clip x can overflow to a large negative value if clip x is INT MAX, bypassing the bounds guard. This allows an unclamped coordinate to be passed through sixel frame clip() to clip(), which calculates a source pointer far beyond the image buffer and passes it to memmove(). An attacker can use a specially crafted crop argument with any valid image to trigger an out-of-bounds read in the heap, leading to a crash and potential information disclosure.

Recommendations Update to version 1.8.7-r1.

Exploit

Fix

Out of bounds Read

Integer Overflow

Weakness Enumeration

CWE-125

CWE-190

Related Identifiers

CVE-2026-33019

Affected Products

Libsixel

References · 10

• 🔥 https://github.com/saitoha/libsixel/security/advisories/GHSA-c854-ffg9-g72c · Exploit
• https://security-tracker.debian.org/tracker/CVE-2026-33019 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-33019 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-33019 · Security Note
• https://ubuntu.com/security/CVE-2026-33019 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2026-33019 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-33019 · Vendor Advisory
• https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1 · Note
• https://twitter.com/VulmonFeeds/status/2044320898170109957 · Twitter Post
• https://twitter.com/CVEnew/status/2044338911699521842 · Twitter Post