Go to homepageCyberStrike

Menu

Star on GitHub · 3.2k
Sign inDownload

CVE-2026-33021

7.3 · HIGH

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel.

Published Apr 14, 2026CWE-416EPSS 0.21%

Overview

CVE-2026-33021 is a high-severity vulnerability. It was published on April 14, 2026 and has a CVSS 3.1 base score of 7.3 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.3, rated HIGH. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical 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 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 has been fixed in version 1.8.7-r1.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/saitoha/libsixel/releases/tag/v1.8.7-r1GitHubgithub.com/saitoha/libsixel/security/advisories/GHSA-j6m5-2cc7-3whc

How CyberStrike helps

Frequently asked questions

What is CVE-2026-33021?

CVE-2026-33021 is a high-severity vulnerability. It was published on April 14, 2026 and has a CVSS 3.1 base score of 7.3 (HIGH).

How severe is CVE-2026-33021?

This vulnerability has a CVSS 3.1 base score of 7.3, rated HIGH. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-33021?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-33021?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-33021 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

Related HIGH CVEs from 2026

View all
Browse by year2026202520242023202220212020201920182017201620152014201320122011201020092008200720062005200420032002200120001999