Medium severity · published Jul 21, 2026
CVE-2026-47251
libheif has an incomplete fix for CVE-2026-3949: integer overflow bypass in vvdec_push_data2
6.1
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 5% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
libheif · strukturag
< 1.22.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-47251
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-47251
Issue Tracking
https://github.com/strukturag/libheif/issues/1712
Exploit
https://github.com/strukturag/libheif/security/advisories/GHSA-p6q9-fhf2-vj9v
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