CVE-2026-47251CWE-125CWE-190

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

Medium · published July 21, 2026

CVSS v4.0
6.8
EPSS
0%
Percentile
4.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
6.8 · MEDIUM
Vector
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N
EPSS
0.00159 · 4.7th percentile
Weaknesses
CWE-125 · Out-of-bounds Read; CWE-190 · Integer Overflow or Wraparound
Published
2026-07-21T21:18Z
EPSS history
Timeline
  • 21 JUL 21:18Z
    libheif has an incomplete fix for CVE-2026-3949: integer overflow bypass in vvdec_push_data2
    cvelistv5