CVE-2026-33018 — Use After Free in Libsixel

CWE-416 — Use After FreeCWE-825 — Expired Pointer Dereference5 documents4 sources
Severity
7.0HIGHNVD
EPSS
0.0%
top 96.99%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
1
Saitoha Libsixel
Timeline
PublishedApr 14
Latest updateApr 15

Description

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_…

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HExploitability: 1.0 | Impact: 5.9

Affected Packages1 packages

▶CVEListV5saitoha/libsixel< 1.8.7-rc1

🔴Vulnerability Details

1
CVEList
libsixel: Use-After-Free in load_gif()↗2026-04-14
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📋Vendor Advisories

1
Red Hat
libsixel: libsixel: Arbitrary code execution via Use-After-Free in GIF processing↗2026-04-14
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💬Community

2
Bugzilla
CVE-2026-33018 libsixel: libsixel: Arbitrary code execution via Use-After-Free in GIF processing [fedora-all]↗2026-04-15
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Bugzilla
CVE-2026-33018 libsixel: libsixel: Arbitrary code execution via Use-After-Free in GIF processing↗2026-04-14
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CVE-2026-33018 — Use After Free in Saitoha Libsixel | cvebase