CVE-2026-55087

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{"affected": [{"affectedData": [{"product": "etherpad", "vendor": "ether", "versions": [{"status": "affected", "version": ">= 2.1.0, < 3.1.0"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Etherpad is a real-time collaborative editor. From 2.1.0 until 3.1.0, Etherpad uses the attacker-controlled x-proxy-path request header in src/node/hooks/express/admin.ts when substituting paths into HTML, JavaScript, and CSS under /admin without sanitization, Vary: x-proxy-path, or Cache-Control: private, no-store. A shared proxy or CDN can cache the resulting response and serve attacker-injected script to an administrator. In src/node/hooks/express/specialpages.ts, version 3.0.0 also accepts a protocol-relative x-proxy-path value when constructing the /p/:pad/timeslider redirect, allowing redirection to an attacker-controlled host. The issues are exploitable when the deployment permits client-supplied x-proxy-path headers to reach Etherpad. This issue is fixed in version 3.1.0."}], "id": "CVE-2026-55087", "lastModified": "2026-09-09T21:15:59.613", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.1, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 2.7, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-55087", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-08-21T20:58:55.152876Z", "version": "2.0.3"}}]}, "published": "2026-08-19T20:17:17.720", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/ether/etherpad/commit/8c6104c5d5daf41f0d454acc04d42dffa0e0d996"}, {"source": "security-advisories@github.com", "url": "https://github.com/ether/etherpad/pull/7784"}, {"source": "security-advisories@github.com", "url": "https://github.com/ether/etherpad/security/advisories/GHSA-fjgc-3mj7-8rg8"}, {"source": "security-advisories@github.com", "url": "https://github.com/ether/etherpad/tree/3.1.0"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}, {"lang": "en", "value": "CWE-444"}, {"lang": "en", "value": "CWE-601"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2.1.0,3.1.0)"}}], "enrichment": {"confidence": 90.0, "confidence_source": "matching", "scores": [{"score": 90.0, "source": "matching"}]}, "original": {"product": "etherpad", "source": "cna", "vendor": "ether"}, "product": "etherpad", "vendor": "etherpad"}], "created": "2026-08-19T23:30:17.089627+00:00", "updated": "2026-08-21T13:03:32.771246+00:00", "vendors": ["etherpad", "etherpad$PRODUCT$etherpad"]}