GIMP icns_plugin OOB Read leaks heap via truncated mask
CVE-2026-66759 Published on July 27, 2026
Gimp: out-of-bounds read in file-icns plugin causes information disclosure or crash on crafted icns images
A flaw was found in the file-icns plugin in GIMP. When applying a decompressed mask during ICNS image processing, the plugin reads from the mask data buffer without verifying if the cursor exceeds the allocated resource size. If a crafted file contains a truncated mask resource, the icns_decompress function continues reading past the bounds of the buffer. This out-of-bounds read vulnerability results in information disclosure of heap contents, where memory contents are leaked as alpha channel pixel values, or a crash leading to a denial of service if unmapped memory is accessed.
Vulnerability Analysis
CVE-2026-66759 can be exploited with local system access, requires user interaction. This vulnerability is considered to have a low attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2026-66759. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity, and a high impact on availability.
Timeline
Reported to Red Hat.
Made public.
Weakness Type
Out-of-bounds Read
The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.
Products Associated with CVE-2026-66759
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