Collabora Online: Reflected HTML injection through host_session_id

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-48164
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-30 15:16:52 UTC
Updated2026-10-30 19:37:07 UTC
DescriptionCollabora 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.

Risk And Classification

Primary CVSS: v3.1 4.7 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

EPSS: 0.003250000 probability, percentile 0.255820000 (date 2026-11-02)

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.7MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
3.1CNADECLARED4.7MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA CollaboraOnline Online affected < 24.04.18 Not specified
CNA CollaboraOnline Online affected >= 25.04.0-0, < 25.04.11 Not specified

References

ReferenceSourceLinkTags
github.com/CollaboraOnline/online/commit/2d4469d27f0c52f4b28b64090e60452... [email protected] github.com
github.com/CollaboraOnline/online/security/advisories/GHSA-wgmm-q3ch-64jj [email protected] github.com
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