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CVE-2026-48164EUVD-2026-114089

Collabora Online: Reflected HTML injection through host_session_id

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 24.04.18, 25.04.11
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

Collabora Online, the browser-based collaborative office suite built on LibreOffice technology, is affected. An attacker can trick a user into opening a crafted link that injects malicious HTML and scripts into the editor page, potentially exposing the user's session token and document content, unless a Content Security Policy blocks the scripts.

Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.

Read the original description

Collabora Online is a collaborative online office suite based on LibreOffice technology. Prior to 24.04.18 and 25.04.11, the `host_session_id` query/form parameter is substituted into the `cool.html` editor page without HTML encoding, unlike parameters passed through the existing variable-encoding mechanism. An attacker who induces a victim to load a crafted URL can inject HTML and, in the absence of an effective `Content Security Policy`, execute scripts in the Collabora Online iframe's origin, exposing the session authentication token and page contents. A reverse proxy that preserves the `Content Security Policy` header sent by `coolwsd` mitigates the script-execution scenario. This issue is fixed in versions 24.04.18 and 25.04.11.

Timeline

  1. CVE published
  2. First seen by cve.now
  3. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  4. Record last updated

Affected versions

  • CollaboraOnline online

    fixed in 24.04.18; From 25.04.0-0 · fixed in 25.04.11

References 2

GitHub · CollaboraOnline/online