# CVE-2026-44638: libsixel: libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel

CVE-2026-44638 is fixed in libsixel on 1 platform by DEBIAN-CVE-2026-44638 (version 1:1.8.7-r2-1), released May 27, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-44638
- Priority: Routine
- CVSS: 2.5 (low)
- EPSS: 0.0013
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 14, 2026

## Description

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From  to 1.8.7-r1, a wrong NULL check after an allocation call in sixel_decode_raw and sixel_decode causes a NULL pointer dereference whenever the allocation fails. The check tests the address of the output parameter (always non-NULL) instead of the value the malloc returned. On allocation failure, the function continues and writes through a NULL pointer, crashing the process. This is a denial of service against any caller of these public APIs that hits a low-memory condition. This vulnerability is fixed in 1.8.7-r2.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libsixel Debian 14 | 1:1.8.7-r2-1 | [DEBIAN-CVE-2026-44638](https://patchblox.com/security/data/fix/linux/debian-cve-2026-44638.md) | May 27, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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