CVE-2026-66759 Gimp: out-of-bounds read in file-icns plugin causes information disclosure or crash on crafted icns images

Description

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.

Exploitable with local access to the machine, without an account and if a user takes an action; an attacker can seriously compromise confidentiality, integrity or availability.

Attack vector

Local

Attack complexity

Low

Privileges required

None

Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

High

Affected products and versions