Answer in brief
CVE-2026-55087 records a Medium severity (CVSS 6.1) vulnerability in Etherpad: x-proxy-path header reflected into admin HTML/JS/CSS (cache-poisoning XSS) and concatenated into redirect (open-redirect). The current sources do not mark it as known exploited. The current feed maps ether/etherpad (generic), ep_etherpad-lite (npm), ep_etherpad-lite (npm). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps ether/etherpad (generic), ep_etherpad-lite (npm), ep_etherpad-lite (npm). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| ether/etherpadgeneric | >= 2.1.0, < 3.1.0 | Not reported |
| ep_etherpad-litenpm | >=2.1.0 <3.1.0 | 3.1.0 |
| ep_etherpad-litenpm | >=2.1.0,<=3.0.0 | 3.1.0 |
Published upstream
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 13, 2026
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.
Quoted source text, attributed separately from HOL analysis.