Cross-site scripting in Rocket.Chat - CVE-2026-47733
Published: November 9, 2026
Vulnerability identifier: #VU163156
CSH Severity: Low
CVSS v4: 2.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N]
CVE-ID: CVE-2026-47733
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows an authenticated attacker to execute arbitrary JavaScript in a viewer's browser session through stored cross-site scripting.
The vulnerability exists due to missing URL protocol sanitization in Rocket.Chat's ImageElement component when rendering links from user-supplied markdown images. An authenticated attacker can post an image with a javascript: URL that executes when a viewer clicks it using a legacy browser that permits JavaScript URLs to open in new tabs.
Affected software
Rocket.Chat
How to mitigate CVE-2026-47733
Install security update from vendor's website.
Rocket.Chat - update to 8.5.0