CVE-2026-47733
Rocket.Chat: Missing URL protocol sanitization in ImageElement allows javascript: URLs in markdown images
- State
- Published
- Severity
- 4.4 Medium
- Published
- Jun 24, 2026
- Updated
- Jun 25, 2026
- Reserved
- May 19, 2026
Description
Rocket.Chat is an open-source, secure, fully customizable communications platform. Prior to 8.5.0, the ImageElement component in packages/gazzodown renders user-controlled src values directly into <a href> and <img src> attributes without protocol sanitization. Unlike the analogous LinkSpan component — which uses sanitizeUrl to block javascript:, data:, and vbscript: protocols — ImageElement passes the raw URL through unchanged. An authenticated user can post a markdown image with a javascript: URL that, if clicked on an older browser, would execute arbitrary JavaScript in the viewer's session. This vulnerability is fixed in 8.5.0.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 4.4 Medium | CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N | GitHub_M |
Weaknesses
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Products
| Product | Versions |
|---|---|
Rocket.ChatRocketChat |
|
References
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