Medium · published October 29, 2025
PrivateBin is an online pastebin where the server has zero knowledge of pasted data. Versions 1.7.7 through 2.0.1 allow persistent HTML injection via the unsanitized attachment filename (attachment_name) when attachments are enabled. An attacker can modify attachment_name before encryption so that, after decryption, arbitrary HTML is inserted unescaped into the page near the file size hint, enabling redirect (e.g., meta refresh) and site defacement and related phishing attacks. Script execution is normally blocked by the recommended Content Security Policy, limiting confidentiality impact. The issue was introduced in 1.7.7 and fixed in 2.0.2. Update to 2.0.2 or later. Workarounds include enforcing the recommended CSP, deploying PrivateBin on a separate domain, or disabling attachments.