Executive Summary

CVE-2025-71330 is a denial of service vulnerability in the image-size library versions 1.1.0 to 1.2.1 and 2.0.0 to 2.0.2. It occurs when a remote attacker supplies a specially crafted ICNS image buffer containing valid magic bytes and a zero-valued entry length field. This causes an infinite loop in the ICNS parser because the offset is never incremented, making the while loop condition true indefinitely. As a result, the Node.js event loop is permanently blocked.

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Impact Analysis

This vulnerability can cause a denial of service by permanently blocking the Node.js event loop. An attacker can exploit this by sending a malformed ICNS image that triggers an infinite loop in the parser, effectively making the affected application unresponsive and unable to process further events or requests.

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Detection Guidance

This vulnerability can be detected by identifying if your system or application is using the image-size library versions 1.1.0 to 1.2.1 or 2.0.0 to 2.0.2, which are affected by the ICNS image parsing issue.

To detect potential exploitation attempts, monitor for Node.js processes that become unresponsive or hang indefinitely, as the vulnerability causes the Node.js event loop to block.

While no specific detection commands are provided, you can use commands to check the installed version of the image-size package, for example:

• npm list image-size
• yarn list image-size

Additionally, monitoring logs or network traffic for malformed ICNS image buffers being processed might help identify exploitation attempts.

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Mitigation Strategies

The immediate mitigation step is to upgrade the image-size library to a version later than 2.0.2 where the vulnerability has been addressed.

If an upgrade is not immediately possible, consider implementing input validation or filtering to block or sanitize ICNS image buffers with suspicious or zero-valued entry length fields before they reach the vulnerable parser.

Also, monitor Node.js processes for hangs or unresponsiveness and restart them as a temporary measure to recover from potential denial of service conditions.

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