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TI-2026-83143 Aliases CVE-2026-48164

Reflected HTML injection in Collabora Online through host_session_id

Priority LOW 22CWE-79Published · Updated

Key facts

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

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

Summary

Collabora Online before 24.04.18 and from 25.04.0-0 before 25.04.11 does not HTML-encode the host_session_id parameter when it is placed into the cool.html editor page. This is an improper neutralization of input during web page generation (CWE-79). An attacker who gets a victim to load a crafted URL can inject HTML and run scripts in the Collabora Online iframe origin when no effective Content Security Policy is present, exposing the session authentication token and page contents. The attack requires user interaction: the victim must load the crafted URL.

Written with Claude Haiku 5.5 from the sources below · 2026-11-05

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00325 25th percentileScored 2026-11-07
Fix Fixed online (CollaboraOnline): 24.04.18, 25.04.11

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
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
Collaboraonlinebefore 24.04.18; 25.04.0-0 to before 25.04.1124.04.18, 25.04.11Patch availableCNA
  • online VendorCollabora Affected before 24.04.18; 25.04.0-0 to before 25.04.11 Fixed in 24.04.18, 25.04.11 Patch available CNA

Remediation

Upgrade Collabora Online to version 24.04.18 or 25.04.11. A reverse proxy that preserves the Content Security Policy header sent by coolwsd mitigates the script-execution scenario.

Written with Claude Haiku 5.5 from the sources below · 2026-11-05

  • Fix · CNA online (CollaboraOnline) Fixed in 24.04.18, 25.04.11

Timeline

  1. 2026-10-30 Threatist record created from CVE-2026-48164
  2. 2026-10-30 CISA SSVC decision points changed

References

Other 2

  • TI-2026-73868 Collabora Online Built-in CODE Server allows remote code execution KEVCVSS 4.0CRITICAL 9.2
  • TI-2026-19024 Collabora Online vulnerable to Authorization Bypass CVSS 3.1MEDIUM 5.3
  • TI-2021-12412 Unauthenticated attacker could gain access to currently open files CVSS 3.1CRITICAL 9.8
  • TI-2025-40711 Configuration-Dependent RCE (OS Command Injection) in richdocumentscode proxy CVSS 4.0HIGH 7.2
  • TI-2023-16934 Collabora Online has Stored Cross-Site-Scripting vulnerability in admin interface CVSS 3.1HIGH 8.7
  • TI-2025-20570 Collabora Online Vulnerable to Arbitrary File Write CVSS 4.0HIGH 8.3
See all 19 →

Sources

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