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

6.8MEDIUM

Key Information:

Vendor

Strukturag

Status
Libheif
Vendor
CVE Published:
21 July 2026

What is CVE-2026-47251?

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 Version(s)

libheif < 1.22.0

References

https://github.com/strukturag/libheif/security/advisories...
x_refsource_CONFIRM
https://github.com/strukturag/libheif/issues/1712
x_refsource_MISC

CVSS V4

Score:
6.8
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.