What’s Vulnerable › Vulnerabilities

CVE-2026-32741: libheif has a heap buffer overflow in decode_mask_image()

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-19 · updated 2026-07-24
• Weakness: CWE-122

Description

libheif is a HEIF and AVIF file format decoder and encoder. Versions 1.21.2 and below contain a heap buffer overflow in MaskImageCodec::decode_mask_image(). When decoding a HEIF file containing a mask image (mski), the function copies the full iloc extent data into a pixel buffer using memcpy(dst, data.data(), data.size()). The copy length data.size() is determined by the iloc extent in the file (attacker-controlled), while the destination buffer is sized based on the declared image dimensions. Because no upper-bound check exists on the data length, a crafted file whose iloc extent exceeds the pixel buffer allocation overflows the heap. The vulnerable single-memcpy branch is reached when the mskC property specifies bits_per_pixel = 8 and the ispe property declares an even width ≥ 64 (so that stride == width), with no changes to default security limits or external codec plugins required. This issue has been fixed in version 1.22.0.

Affected products

• strukturag libheif: before 1.22.0

References

• https://github.com/strukturag/libheif/releases/tag/v1.22.0
• https://github.com/strukturag/libheif/security/advisories/GHSA-j3w5-7whq-p37q
• https://access.redhat.com/security/cve/CVE-2026-32741
• https://bugzilla.redhat.com/show_bug.cgi?id=2480002
• https://github.com/strukturag/libheif/security/advisories/GHSA-j3w5-7whq-p37q
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32741.json

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