CVE-2026-33018

HIGHNVD 7.07.0—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.0 under NVD CVSS v3. EPSS exploit probability: 0.0%, top 93% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
7.0
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.0Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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_get_pixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixel_helper_load_image_file() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1.

CVSS v3
7.0
EG Score
7.0(medium)
EPSS
9.0%
KEV
Not listed

Published

April 14, 2026

Last Modified

April 23, 2026

Advisory Details (2)

Auto-updated Jun 14, 2026
🔬 Proof of concept available. Patch available. Sources: github_release, github.
github Patch Available🟡 PoC Available

Use-After-Free in load_gif() · Advisory · saitoha/libsixel · GitHub

https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp
github_release Patch Available

v1.8.7-r1 security update

Patch available: saitoha/libsixel v1.8.7-r1

https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 43× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-18 10:04 UTCEPSS rescore
  2. 2026-07-18 10:04 UTCEPSS rescore
  3. 2026-07-16 17:03 UTCEPSS rescore
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  1. 2026-06-29 14:06 UTCEPSS rescore
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  22. 2026-06-16 17:52 UTCEPSS rescore
  23. 2026-06-15 17:49 UTCEPSS rescore
  24. 2026-06-14 23:18 UTCEPSS rescore
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  66. 2026-05-20 17:14 UTCEG score recompute
  67. 2026-05-20 11:22 UTCEPSS rescore
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  69. 2026-05-20 11:21 UTCEPSS rescore
  70. 2026-05-18 21:31 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-33018?
CVE-2026-33018 is a high vulnerability published on April 14, 2026. 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 loadgif() function in fromgif.c, where a single sixelframet object is reused across all frames of an animated GIF and gifinitframe() unconditionally…
When was CVE-2026-33018 disclosed?
CVE-2026-33018 was first published in the National Vulnerability Database on April 14, 2026, with the most recent update on April 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33018 actively exploited?
CVE-2026-33018 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 9.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-33018?
CVE-2026-33018 has a CVSS v3 base score of 7.0 (NVD).
How do I remediate CVE-2026-33018?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33018, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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