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Critical CVSS 9.6

CVE-2026-55085

NVD analysis in progress

Etherpad is a real-time collaborative editor. Prior to 3.3.1, result.appendSpan in src/static/js/domline.ts interpolates the start attribute of a numbered list directly into an unquoted ol start attribute before assigning the generated markup to node.innerHTML. ImportEtherpad.setPadRaw in src/node/utils/ImportEtherpad.ts accepts attacker-controlled attribute-pool values from a crafted .etherpad import, including list:number1 and a malicious start value. Any user with write access to a pad can store markup that executes as cross-site scripting when another user opens the pad or /timeslider, including when an administrator views the pad. This issue is fixed in version 3.3.1.

What this means

Exposure
Exploitable remotely over the network and without authentication — but only if a user opens booby-trapped content.
Impact
An attacker can read sensitive data, modify or destroy data and degrade the service. The impact spreads beyond the vulnerable component into other parts of the system.
Weakness
Attacker-supplied script runs in other users’ browsers (cross-site scripting).
Likelihood
Its EPSS score stays low: nothing points to imminent exploitation, which is no reason to leave it unpatched.

What to doPatch without waiting for the next scheduled cycle.

Read automatically from the CVSS vector, the weakness type (CWE) and the EPSS score. The technical description above remains the one published by NIST.

Published
19 August 2026
CVSS
9.6 (v3.1) CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L
EPSS
0.36% probability of exploitation within 30 days · above 29% of all CVEs
Weakness
CWE-79
Sources
nvd
References

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