CVE-2026-49864: Butlerx Wetty

High severity, CVSS 8.6. EPSS: 0.4% chance of exploitation in the next 30 days.

wetty provides terminal access in browser over http/https. Prior to version 3.0.4, the wetty client decodes a base64 filename from the file-download escape sequence and interpolates it raw into a Toastify HTML string (`escapeMarkup: false`). Any output the victim renders - a `cat`'d file, a tailed log, an SSH MOTD, a `curl` response - that contains `\x1b[5i...:...\x1b[4i` runs script in the wetty origin and types attacker-chosen keystrokes into the victim's SSH session. Version 3.0.4 fixes the issue.

Affected products

• Butlerx Wetty: before 3.0.4 (fixed in 3.0.4)

Published 2026-08-13. Last modified 2026-09-09.