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Vulnerability record · CVE-2026-32741 · published 19 May 2026

CVE-2026-32741: Heap-based buffer overflow vulnerability

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.

7.1 CVSS 3.1 High EPSS 0.45% · top 63.5% CWE-122 · Heap-based buffer overflowCWE-120 · Classic buffer overflow Deferred
7.1CVSS 3.1 base score
0.45%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
6References
24 Jul 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H

References

LinkTags
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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Source: NIST National Vulnerability Database (record CVE-2026-32741), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.