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.

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required Low

Scope Changed

Confidentiality Impact Low

Integrity Impact Low

Availability Impact None

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Affected Vendors & Products

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Vendors Products
References
Link Providers
https://github.com/RocketChat/Rocket.Chat/security/advisories/GHSA-vvrf-fq54-q4pr cve-icon
History

Wed, 24 Jun 2026 21:15:00 +0000

Type Values Removed Values Added
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.
Title Rocket.Chat: Missing URL protocol sanitization in ImageElement allows javascript: URLs in markdown images
Weaknesses CWE-79
References
Metrics cvssV3_1

{'score': 4.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N'}
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-24T20:51:29.245Z

Reserved: 2026-05-19T22:16:39.503Z

Link: CVE-2026-47733

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

Updated: 2026-06-25T01:00:04Z