CVE-2025-5473: GIMP ICO File Parsing RCE Vulnerability

CVE-2025-5473 Overview

CVE-2025-5473 is an integer overflow vulnerability in GIMP's ICO file parsing functionality that enables remote code execution. This vulnerability allows remote attackers to execute arbitrary code on affected installations of GIMP. User interaction is required to exploit this vulnerability—the target must visit a malicious page or open a malicious ICO file.

The specific flaw exists within the parsing of ICO files. The issue results from the lack of proper validation of user-supplied data, which can result in an integer overflow before writing to memory. An attacker can leverage this vulnerability to execute code in the context of the current process. This vulnerability was tracked as ZDI-CAN-26752 by the Zero Day Initiative.

Critical Impact

Remote code execution through maliciously crafted ICO files allows attackers to gain full control of victim systems running vulnerable GIMP versions, potentially leading to data theft, malware deployment, or lateral movement within networks.

Affected Products

• GIMP (all versions prior to patched release)

Discovery Timeline

• 2025-05-18 - GIMP releases version 3.0.4 with security fixes
• 2025-06-06 - CVE-2025-5473 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-5473

Vulnerability Analysis

This vulnerability is classified as CWE-190 (Integer Overflow or Wraparound). The flaw resides in GIMP's ICO file parsing routines, where insufficient validation of user-controlled data leads to an integer overflow condition. When processing a specially crafted ICO file, the parser fails to properly validate size-related fields, allowing an attacker to trigger an integer overflow that corrupts memory allocation calculations.

The vulnerability requires user interaction, meaning the victim must open a malicious ICO file or visit a webpage that triggers the file parsing. Once exploited, the attacker gains the ability to execute arbitrary code with the same privileges as the GIMP process, which typically runs with the current user's permissions.

Root Cause

The root cause of CVE-2025-5473 is improper input validation in GIMP's ICO file parsing code. When processing ICO files, the parser reads size and dimension values from the file without adequate bounds checking. These values are used in arithmetic operations to calculate memory allocation sizes. By providing specially crafted values, an attacker can cause an integer overflow, resulting in a smaller-than-expected buffer allocation. Subsequent write operations then exceed the allocated buffer boundaries, corrupting heap memory and enabling code execution.

Attack Vector

The attack vector is network-based, requiring the victim to open a malicious ICO file. Attack scenarios include:

1. Email attachment - Attacker sends a malicious ICO file disguised as a legitimate image or embedded within a document
2. Web-based delivery - Victim browses to a malicious website hosting the crafted ICO file
3. File sharing - Malicious ICO file distributed through file sharing platforms or repositories

The vulnerability exploits the integer overflow during ICO file parsing. When GIMP processes the malicious file, the crafted size values trigger an integer wraparound, leading to heap corruption. The attacker can then leverage this memory corruption primitive to achieve arbitrary code execution within the context of the GIMP process.

Detection Methods for CVE-2025-5473

Indicators of Compromise

• Unexpected GIMP process crashes when opening ICO files
• Anomalous child processes spawned from GIMP
• Suspicious network connections originating from GIMP processes
• Unusual memory access patterns or heap corruption artifacts in crash dumps

Detection Strategies

• Monitor for abnormal GIMP process behavior, including unexpected crashes or memory access violations
• Implement file inspection for malformed ICO files with anomalous header values or size fields
• Deploy endpoint detection rules to identify suspicious process chains where GIMP spawns unexpected child processes
• Use application whitelisting to restrict unauthorized code execution from image editing contexts

Monitoring Recommendations

• Enable crash reporting and analyze GIMP crash dumps for exploitation indicators
• Monitor file system access for ICO files from untrusted sources
• Deploy network monitoring to detect suspicious download patterns of ICO files
• Implement SentinelOne's behavioral AI to detect post-exploitation activities following GIMP process compromise

How to Mitigate CVE-2025-5473

Immediate Actions Required

• Update GIMP to version 3.0.4 or later immediately
• Avoid opening ICO files from untrusted or unknown sources
• Configure email filtering to quarantine or scan ICO file attachments
• Implement web content filtering to block ICO downloads from untrusted domains
• Deploy SentinelOne endpoint protection with behavioral detection enabled

Patch Information

GIMP has released version 3.0.4 which addresses this vulnerability. Organizations should update to this version or later to remediate CVE-2025-5473. The fix implements proper validation of size fields in ICO file headers to prevent integer overflow conditions. For detailed information, see the GIMP Release Announcement and the Zero Day Initiative Advisory ZDI-25-321. Debian users should refer to the Debian LTS Announcement for package updates.

Workarounds

• Disable ICO file associations with GIMP until patching is complete
• Use alternative image viewers for ICO files that are not affected by this vulnerability
• Implement application sandboxing to limit the impact of potential exploitation
• Configure firewall rules to restrict outbound connections from GIMP processes
• Deploy strict least-privilege policies for user accounts that run GIMP

Organizations should prioritize patching as the primary remediation strategy. Workarounds provide temporary risk reduction but do not fully address the underlying vulnerability.