Description

CERT Polska has received a report about vulnerability in MTW CleanShot X software and participated in coordination of its disclosure.

The vulnerability CVE-2026-16477: CleanShot X for macOS insecurely deserializes untrusted data embedded in a .cleanshot project file (editable screenshot annotations). Exploitation requires an attacker to craft a malicious .cleanshot file, deliver it to the target, and have the target open it; the payload is then executed automatically during parsing, resulting in arbitrary code execution in the context of the current user. Users who have never opened a .cleanshot file from an untrusted source are not affected by this vulnerability.

This vulnerability was fixed in versions: 4.5.2, 4.6.3, 4.7.8 and 4.8.10

Credits

We thank Dharan24 for finding the vulnerability.