Cross-site Scripting (XSS) Affecting rabbitmq-server package, versions *


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.3% (20th percentile)

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  • Snyk IDSNYK-ECHOLATEST-RABBITMQSERVER-20138289
  • published25 Sept 2026
  • disclosed23 Sept 2026

Introduced: 23 Sep 2026

NewCVE-2026-66077  (opens in a new tab)
CWE-79  (opens in a new tab)

How to fix?

There is no fixed version for Echo:latest rabbitmq-server.

NVD Description

Note: Versions mentioned in the description apply only to the upstream rabbitmq-server package and not the rabbitmq-server package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

RabbitMQ is a messaging and streaming broker. Prior to versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6, The management UI uses EJS 1.0 in which <%= ... %> does NOT HTML-escape. connection.ejs:135 renders <%= connection.ssl_details.peer_cert_subject %> (and peer_cert_issuer) directly into the page. The same pattern appears in streamConnection.ejs:102,106,110. The values come from rabbit_ssl:peer_cert_subject/1 which formats the DN as a string without HTML escaping. The verifier corrected the original researcher's claim: this is reachable only when the listener is configured with verify_peer (so the certificate must be signed by a CA in the broker's trust store, not arbitrary self-signed); however, in deployments using mTLS for client authentication, any user who can request a certificate from the organisational CA controls the Subject CN. An attacker who can obtain a TLS client certificate signed by a CA the broker trusts (with verify_peer enabled) can embed JavaScript in the certificate's Subject DN. When any administrator views that connection in the management UI, the script executes in the admin's browser session, allowing full account takeover (create users, export definitions, etc.). The management UI's CSP includes 'unsafe-inline', so inline script execution is not blocked. Preconditions include TLS listener configured with ssl_options.verify = verify_peer Attacker can obtain a CA-signed client certificate with attacker-chosen Subject (e.g. self-service corporate PKI, or rabbitmq_trust_store plugin in use) Administrator views the connection detail page. This issue is fixed in versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6.

CVSS Base Scores

version 3.1