{"id":"CVE-2026-48164","title":"Collabora Online: Reflected HTML injection through host_session_id","summary":"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, un…","severity":"medium","cvss":4.7,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N","cvssSource":"cna","cwe":["CWE-79"],"vendor":"CollaboraOnline","product":"online","affected":["online < 24.04.18","online >= 25.04.0-0, < 25.04.11"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-10-30T15:44:14.478525Z"},"published":"2026-10-30","updated":"2026-10-30","sourceUpdated":"2026-10-30T15:44:29.766Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-48164","references":[{"url":"https://github.com/CollaboraOnline/online/security/advisories/GHSA-wgmm-q3ch-64jj","label":"https://github.com/CollaboraOnline/online/security/advisories/GHSA-wgmm-q3ch-64jj"},{"url":"https://github.com/CollaboraOnline/online/commit/2d4469d27f0c52f4b28b64090e60452d2e147279","label":"https://github.com/CollaboraOnline/online/commit/2d4469d27f0c52f4b28b64090e60452d2e147279"}],"tags":["cve.org"],"epss":0.00325,"epssPercentile":0.25696,"ingestedAt":"2026-11-05T16:07:30.466Z","slug":"CVE-2026-48164","body":"## Overview\n\nCollabora 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.\n\n## Affected\n\n- `online < 24.04.18`\n- `online >= 25.04.0-0, < 25.04.11`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":26,"depthScoreParts":{"impact":25.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}