Incorrect Bitwise Shift of Integer in libheif - #VU153980
Published: October 8, 2026
Vulnerability identifier: #VU153980
CSH Severity: Medium
CVSS v4: 5.6 [CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-1335
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to trigger undefined behavior during image decoding.
The vulnerability exists due to an incorrect bitwise shift of an integer in ImageItem_Grid::decode_and_paste_tile_image() in libheif/image-items/grid.cc when computing the opaque alpha value for a grid image tile with a 64-bit alpha component. A remote attacker can supply a specially crafted image file that causes a shift by 64 bits to trigger undefined behavior during image decoding.
Exploitation requires user interaction and a build without assertions and with the uncompressed codec enabled through WITH_UNCOMPRESSED_CODEC. The uncompressed codec is disabled in the default build configuration.
Affected software
libheif
Remediation
Install security update from vendor's website.
libheif - update to 1.23.6