A stored cross‑site scripting flaw exists in the annotation guide feature of CVAT. Attacks that can create or edit an annotation guide on a task may insert malicious JavaScript, which then executes in the browser whenever anyone opens that guide. The injected code can perform arbitrary requests using the victim’s account credentials, enabling the attacker to read or modify data, or potentially alter the system’s configuration. This results in a loss of confidentiality, integrity, and availability of the data accessed by the victim’s session.

CVAT version 2.5.0 through 2.63.0 is affected. The product is maintained by cvat‑ai and released as open‑source software. Any installation using these versions that allows users to create or edit annotation guides is vulnerable.

The flaw carries a CVSS score of 8.5 and is not listed in CISA KEV. The EPSS score is not available, indicating no publicly known exploitation data yet. Exploitation requires that the attacker has permissions to create or edit a guide and that a victim subsequently views the guide in a browser. Because the code executes within the target’s session, an attacker can perform further actions on behalf of that user. Although the vulnerability is browser‑based, the high severity and potential for privilege escalation warrant prompt attention.