--- title: "CVE-2026-66077\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2026-66077?format=md keywords: index, follow --- # CVE-2026-66077 Publication date 24 September 2026 Last updated 24 September 2026 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) Toggle side navigation ## Description 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. ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | rabbitmq-server | 26.04 LTS resolute | Needs evaluation | | 24.04 LTS noble | Needs evaluation | | 22.04 LTS jammy | Needs evaluation | | 20.04 LTS focal | Needs evaluation | | 18.04 LTS bionic | Needs evaluation | | 16.04 LTS xenial | Needs evaluation | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) ## Severity score breakdown CVSS version: CVSS v4.0 **Base score** 7.3 · High * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | Low | | Attack requirements | Present | | Privileges required | Low | | User interaction | Active | | Vulnerable system - Confidentiality impact | High | | Vulnerable system - Integrity impact | High | | Vulnerable system - Availability impact | Low | | Subsequent system - Confidentiality impact | None | | Subsequent system - Integrity impact | None | | Subsequent system - Availability impact | None | * Scores | Parameter | Value | | --- | --- | | Base score | 7.3 · High | | Base + Threat score | - | | Base + Environmental score | - | | Base + Threat + Environmental score | - | **Vector:** CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-66077) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-66077) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-66077) * [Debian](https://security-tracker.debian.org/tracker/CVE-2026-66077) ### Other references * * *