What’s Vulnerable › Vulnerabilities

CVE-2026-47251: libheif has an incomplete fix for CVE-2026-3949: integer overflow bypass in vvdec_push_data2

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-21 · updated 2026-10-24
• Weakness: CWE-125

Description

libheif is a HEIF and AVIF file format decoder and encoder. The fix for CVE-2026-3949 (commit `b97c8b5`, PR #1712) introduced an integer overflow in the very security check it added. The check itself can be bypassed, allowing a crafted HEIF file with a VVC track to trigger the same out-of-bounds heap read that CVE-2026-3949 was meant to prevent. This is a separate, currently-unpatched vulnerability. Issue #1712 was closed as fixed without testing the edge case where `size` is near `UINT32_MAX`. Version 1.22.0 patches the issue.

Affected products

• strukturag libheif: before 1.22.0 — fixed in 1.22.0

How to fix

Upgrade to a fixed version: strukturag libheif 1.22.0. Check the vendor advisory for mitigations.

References

• https://github.com/strukturag/libheif/issues/1712
• https://github.com/strukturag/libheif/security/advisories/GHSA-p6q9-fhf2-vj9v
• https://github.com/strukturag/libheif/issues/1712
• https://github.com/strukturag/libheif/security/advisories/GHSA-p6q9-fhf2-vj9v

Get alerted when CVE-2026-47251 or the next vulnerability affects your stack