CVE-2026-62377 Denial of service in libheif
A crafted HEIF file causes libheif to crash via assertion failure or undefined behavior, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-62377?
CVE-2026-62377 is a medium-severity denial of service vulnerability in strukturag libheif, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
libheif is a HEIF and AVIF file format decoder and encoder. In 1.23.0 and earlier, a crafted HEIF sequence accepted by heif_context_read_from_memory() can leave the context with no registered sequence tracks and crash when heif_context_get_track(ctx, 0) is called. HeifContext::get_track() in libheif/context.cc executes assert(has_sequence()) before its normal error handling, so assert-enabled builds abort instead of allowing the public wrapper in libheif/api/libheif/heif_sequences.cc to return null. In release builds, removing the assertion lets the track_id zero path dereference m_tracks.begin()->second on an empty map, which is undefined behavior and typically crashes. The issue is reachable through documented public APIs after parsing attacker-controlled bytes. This issue is fixed in version 1.23.1.
Which versions are affected by CVE-2026-62377?
How do I fix CVE-2026-62377?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-62377 being exploited?
There is no known exploitation of CVE-2026-62377 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-62377, DEBIAN-CVE-2026-62377, GHSA-9ww4-9v47-m7pj, MINI-5cf5-4cpw-35m7, UBUNTU-CVE-2026-62377.