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TI-2026-35234 Aliases CVE-2026-47733

Rocket.Chat: Missing URL protocol sanitization in ImageElement allows javascript: URLs in markdown images

Priority MEDIUM 54CWE-79Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
Required
Attack complexity
High
Impact type
Cross-site scripting
Confidentiality · integrity · availability
Low · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-79.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00141 3rd percentileScored 2026-11-07
Fix Fixed Rocket.Chat (RocketChat): 8.5.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
RocketChatRocket.Chatbefore 8.5.08.5.0Patch availableCNA
  • Rocket.Chat VendorRocketChat Affected before 8.5.0 Fixed in 8.5.0 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:rocket.chat:rocket.chat:*:*:*:*:*:*:*:*——Rocket.Chat
  • cpe:2.3:a:rocket.chat:rocket.chat:*:*:*:*:*:*:*:* Versions — — ·Rocket.Chat

Remediation

  • Fix · CNA Rocket.Chat (RocketChat) Fixed in 8.5.0

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-47733

References

Other 1

  • TI-2026-33430 Rocket.Chat: Pre-Auth NoSQL Injection in CAS Login Handler leading to Arbitrary CAS/SAML User Session Hijack CVSS 3.1CRITICAL 9.1
  • TI-2026-33431 Rocket.Chat: Pre-Auth NoSQL Injection in OAuth2 Token Endpoint leading to Arbitrary User ATO CVSS 3.1CRITICAL 9.1
  • TI-2026-18910 Rocket.Chat Unauthorized Access to OAuth App Details CVSS 3.1HIGH 7.7
  • TI-2026-22776 Rocket.Chat: Users can login with any password via the EE ddp-streamer-service CVSS 4.0CRITICAL 9.3
  • TI-2026-40188 Rocket.Chat: Email Parameter Fallback Leads To Account Takeover Within Apple OAuth CVSS 4.0CRITICAL 9.3
  • TI-2026-34135 Rocket.Chat: SAML signature validation skipped when IdP certificate field is empty CVSS 4.0CRITICAL 9.3
See all 20 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences