{"apiVersion":"1.0","identifier":"CVE-2026-55087","description":"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.","publishedAt":"2026-08-19T20:17:17","lastModifiedAt":"2026-08-21T22:16:40","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-55087","cvssScore":6.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","epssProbability":0.00523,"riskScore":0.64,"affectedProduct":"Etherpad","affectedVersions":">=2.1.0,<3.1.0","vulnerabilityType":"Web app","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-55087","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-55087","en":"https://www.redsauce.net/en/cves/CVE-2026-55087","fr":"https://www.redsauce.net/fr/cves/CVE-2026-55087","pt":"https://www.redsauce.net/pt/cves/CVE-2026-55087","de":"https://www.redsauce.net/de/cves/CVE-2026-55087","sk":"https://www.redsauce.net/sk/cves/CVE-2026-55087","el":"https://www.redsauce.net/el/cves/CVE-2026-55087"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-55087"}}