What’s Vulnerable › Vulnerabilities

CVE-2026-50142: libheif: unbounded heap allocation in HEIF sequence parser (stsz fixed-size mode missing bound check)

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-18 · updated 2026-10-22
• Weakness: CWE-190

Description

libheif is a HEIF and AVIF file format decoder and encoder. From 1.19.0 until 1.23.0, a crafted HEIF sequence accepted by heif_context_read_from_memory() with the msf1 sequence brand can cause unbounded heap allocation. In libheif/sequences/seq_boxes.cc, Box_stsz::parse() applies max_sequence_frames only to variable-size samples, so fixed-size mode accepts an attacker-controlled sample_count without a bound. In libheif/sequences/track.cc, Track::load() also adds current_sample_idx and samples_per_chunk in 32-bit arithmetic, allowing the consistency check to be bypassed by wraparound. The resulting values reach the Chunk::Chunk() allocation path, which can consume gigabytes of memory and crash or stall the process through memory exhaustion. This issue is fixed in version 1.23.0.

Affected products

• strukturag libheif: from 1.19.0, < 1.23.0

References

• https://github.com/strukturag/libheif/commit/a6caa38f7a70d66dc9caec2a7bfe20935b32c622
• https://github.com/strukturag/libheif/releases/tag/v1.23.0
• https://github.com/strukturag/libheif/security/advisories/GHSA-jvmp-j3cw-84mh

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