CVE-2026-62291
Medium · CVSS 5.3Published 2026-08-18
CVSS
5.3
Medium
EPSS
—
exploit probability
Active Exploit
No
not yet listed
What is CVE-2026-62291?
libheif is a HEIF and AVIF file format decoder and encoder. In 1.23.0 and earlier, a crafted image sequence with a 2x2 primary plane and a 256x256 auxiliary alpha plane can cause attacker-controlled heap corruption during a normal decode and re-encode workflow. Track_Visual::decode_next_image_sample() calls transfer_channel_from_image_as() without checking that the auxiliary alpha dimensions match the main frame. The resulting inconsistent image reaches heif_track_decode_next_image() and then heif_context_encode_image(). In unc_encoder::encode(), unc_encoder_component_interleave::encode_tile() sizes its buffer with compute_tile_data_size_bytes() using the primary dimensions but copies each component using its actual plane dimensions. The oversized alpha plane is therefore copied beyond the allocation, causing an out-of-bounds write; the inverse size mismatch can also produce an out-of-bounds read. This issue is fixed in version 1.23.1.
CVSS Score Explained
CVSS 5.3 is Medium severity. Exploitation usually requires some specific conditions (local access, user interaction, or a particular config). Still worth patching in your next maintenance window.
EPSS Exploitation Probability
No EPSS score yet — model needs more data on this CVE.
References & Patches
- ›https://github.com/strukturag/libheif/commit/ac5521ad50399885de96bb6a0733a5d2442740f9
- PATCHhttps://github.com/strukturag/libheif/releases/tag/v1.23.1
- ›https://github.com/strukturag/libheif/security/advisories/GHSA-xpw3-9rhw-482x
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