cvedb.io
CVE-2026-33021
HIGH · CVSS 7.3
EPSS exploitation probability: 0%
Published 2026-04-14T23:16:27.660 · Last modified 2026-06-17T10:36:47.673

Summary

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain a use-after-free vulnerability in sixel_encoder_encode_bytes() because sixel_frame_init() stores the caller-owned pixel buffer pointer directly in frame->pixels without making a defensive copy. When a resize operation is triggered, sixel_frame_convert_to_rgb888() unconditionally frees this caller-owned buffer and replaces it with a new internal allocation, leaving the caller with a dangling pointer. Any subsequent access to the original buffer by the caller constitutes a use-after-free, confirmed by AddressSanitizer. An attacker who controls incoming frames can trigger this bug repeatedly and predictably, resulting in a reliable crash with potential for code execution. This issue

Affected products

saitoha — libsixel

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.