Pandora’s PDF download feature validates only the internal content of a file as PDF, but does not enforce a MIME type or filename when serving the file. A stored cross‑site scripting flaw exists because a maliciously crafted PDF/polyglot file can be uploaded, stored, and later downloaded infected. When the download endpoint serves the file, Flask infers the MIME type from the filename. If the filename or extension causes a different MIME type to be used—such as text/html—the file is rendered inline by the victim’s browser. The attacker’s script then runs with the victim’s session credentials, potentially giving the attacker access to application data or the ability to perform privileged actions. The flaw is a classic example of a stored XSS (CWE‑79) that can lead to session hijacking or other data compromise.

Pandora Analysis, version information not disclosed. Any installation that uses the /task-download/<task_id>/.../pdf endpoint for PDF downloads is potentially affected.

The vulnerability scores a 6.9 on the CVSS scale, indicating moderate to high risk. There is no EPSS score available, and the flaw is not listed in the CISA KEV catalog. The likely attack vector is through the upload interface: an attacker with permission to submit a file can upload a malicious PDF that, once downloaded by a user, will trigger script execution. Given the stored nature of the flaw, persistent exploitation is possible as long as the file remains stored in the system. The absence of a known public exploit does not diminish the risk because the conditions for exploitation—file upload and later download—are common in normal usage.