--- title: "CVE-2026-66071\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-2026-66071?format=md keywords: index, follow --- # CVE-2026-66071 Publication date 29 September 2026 Last updated 29 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. From 3.13.0 until 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1, Atom exhaustion: OAuth2 JWT tag: scope values. extractscopes/1 parses scopes of the form .tag: and calls rabbitdatacoercion:toatom() to convert to a tag atom. The token signature is verified first, so the attacker cannot forge scopes , but in IdP configurations where scope content is user-influenced, each login with a novel tag value leaks one In deployments where users can influence the scopes included in their IdP-issued JWT rabbitmqauthbackendoauth2 enabled IdP permits attacker-influenced scope values in signed tokens. This issue is fixed in versions 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1. ## 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** 6.0 · Medium * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | Low | | Attack requirements | Present | | Privileges required | Low | | User interaction | None | | Vulnerable system - Confidentiality impact | None | | Vulnerable system - Integrity impact | None | | Vulnerable system - Availability impact | High | | Subsequent system - Confidentiality impact | None | | Subsequent system - Integrity impact | None | | Subsequent system - Availability impact | None | * Scores | Parameter | Value | | --- | --- | | Base score | 6.0 · Medium | | Base + Threat score | - | | Base + Environmental score | - | | Base + Threat + Environmental score | - | **Vector:** CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-66071) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-66071) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-66071) * [Debian](https://security-tracker.debian.org/tracker/CVE-2026-66071) ### Other references * * * * * *