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.
CSIRTS triage
- What
- libheif incorrectly handles certain image transforms and malformed images, leading to denial of service or arbitrary code execution.
- Who is affected
- Systems using libheif on Ubuntu 18.04 LTS, 20.04 LTS, 22.04 LTS, and 24.04 LTS are affected.
- Urgency
- Moderate urgency; arbitrary code execution is possible in Ubuntu 24.04 LTS and denial of service in earlier versions.
- Action
- Apply security updates from Ubuntu for libheif across all affected LTS releases.
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Exploitation outlook
- Low exploitation risk0.13% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all EPSS-scored CVEs.
Advisory coverage (2)
- unknownUSN-8683-1: libheif vulnerabilitiesubuntu · 2026-08-26
- mediumCVE-2026-62291: libheif is a HEIF and AVIF file format decoder and encoder. In 1.23.0 and earlier, a crafted i…nvd · 2026-08-18
External references
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