CVE-2026-2271: GIMP PSP File Parser DoS Vulnerability

CVE-2026-2271 Overview

A flaw was found in GIMP's PSP (Paint Shop Pro) file parser. A remote attacker could exploit an integer overflow vulnerability in the read_creator_block() function by providing a specially crafted PSP image file. This vulnerability occurs when a 32-bit length value from the file is used for memory allocation without proper validation, leading to a heap overflow and an out-of-bounds write. Successful exploitation could result in an application level denial of service.

Critical Impact

This integer overflow vulnerability in GIMP's PSP file parser can cause application crashes through heap corruption when processing maliciously crafted image files.

Affected Products

• GIMP (GNU Image Manipulation Program) - versions with vulnerable PSP file parser

Discovery Timeline

• 2026-03-26 - CVE-2026-2271 published to NVD
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2026-2271

Vulnerability Analysis

This vulnerability represents an integer overflow (CWE-190) condition within GIMP's Paint Shop Pro (PSP) file format parser. The flaw resides specifically in the read_creator_block() function, which is responsible for parsing creator metadata blocks within PSP image files.

When GIMP processes a PSP file, it reads a 32-bit length value directly from the file data to determine how much memory to allocate for storing creator block information. The vulnerability arises because this length value undergoes insufficient validation before being used in memory allocation operations. An attacker can craft a PSP file with a malicious length value that, when processed, causes an integer overflow during size calculations.

The integer overflow leads to allocating a significantly smaller buffer than intended. Subsequent write operations then exceed the allocated buffer boundaries, resulting in a heap-based buffer overflow and out-of-bounds write condition. While the attack requires local access and user interaction (opening the malicious file), it can reliably crash the application.

Root Cause

The root cause is improper input validation of untrusted data from PSP image files. Specifically, the read_creator_block() function fails to adequately validate 32-bit length values before using them for memory allocation calculations. When arithmetic operations on these values overflow the 32-bit integer range, the resulting allocation size wraps around to a much smaller value, creating a classic integer overflow to heap overflow exploitation primitive.

Attack Vector

The attack requires local access to the target system and user interaction. An attacker must craft a malicious PSP (Paint Shop Pro) image file containing a specially constructed creator block with an oversized length field designed to trigger the integer overflow. The victim must then open this file using GIMP, either by double-clicking the file, using File > Open, or through drag-and-drop operations.

The attack flow proceeds as follows: the malicious PSP file contains a creator block with a length value crafted to overflow during size calculations. When GIMP's PSP parser processes this block via read_creator_block(), the overflow causes undersized memory allocation. Subsequent data copying exceeds buffer boundaries, corrupting heap memory and causing application instability or crash.

Detection Methods for CVE-2026-2271

Indicators of Compromise

• Unexpected GIMP application crashes when opening PSP format image files
• Crash reports referencing the read_creator_block() function or PSP file parsing routines
• Unusually large or malformed PSP files received via email or downloaded from untrusted sources

Detection Strategies

• Monitor for GIMP process crashes with heap corruption signatures in crash dumps
• Implement file scanning for PSP files with anomalous creator block length values
• Deploy endpoint detection rules for suspicious PSP file attributes (abnormal size ratios, malformed headers)

Monitoring Recommendations

• Enable application crash reporting and centralized logging for GIMP instances
• Monitor file system activity for PSP files from untrusted sources being accessed by GIMP
• Review GIMP crash logs for patterns indicative of exploitation attempts against file parsers

How to Mitigate CVE-2026-2271

Immediate Actions Required

• Exercise caution when opening PSP files from untrusted or unknown sources
• Consider temporarily disabling PSP file format support if not required for workflows
• Update GIMP to the latest available version once patches are released
• Implement application sandboxing to limit the impact of potential exploitation

Patch Information

Security advisories and bug tracking for this vulnerability are available through Red Hat CVE-2026-2271 Advisory, Red Hat Bug Report #2438429, and GNOME GIMP Issue #15732. Monitor these resources for patch availability and update instructions.

Workarounds

• Avoid opening PSP format files from untrusted sources until a patch is available
• Convert PSP files using alternative trusted applications before importing into GIMP
• Use file integrity monitoring to detect potentially malicious PSP files before opening
• Run GIMP in a sandboxed environment or virtual machine when processing files from unknown sources