What’s Vulnerable › Vulnerabilities

CVE-2026-67236: RabbitMQ: Plaintext username:password stored in an insecure cookie after successful POST /login

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-25 · updated 2026-10-15
• Weakness: CWE-312

Description

RabbitMQ is a messaging and streaming broker. From 4.2.0 until 4.2.8 and 4.3.2, a successful POST /login caused is_authorized/2 to set an auth cookie containing base64-encoded username:password credentials without HttpOnly, Secure, SameSite, or expiration protections. Because base64 is encoding rather than encryption, an attacker with same-origin cross-site scripting, an HTTP-readable network position, or local access to the browser cookie store could recover the actual login credentials; older browsers that treated an absent SameSite attribute as None also sent the cookie cross-site. This issue is fixed in versions 4.2.8 and 4.3.2.

Affected products

• rabbitmq-server: from 4.2.0 before 4.2.8; from 4.3.0 before 4.3.2 — fixed in 4.2.8, 4.3.2

How to fix

Upgrade to a fixed version: rabbitmq-server 4.2.8, 4.3.2. Check the vendor advisory for mitigations.

References

• https://github.com/rabbitmq/rabbitmq-server/commit/df9e7f4c0afd311a672705f020d301efad355745
• https://github.com/rabbitmq/rabbitmq-server/commit/edf1fbc7217aaf736955d2e13c9534901a2e0778
• https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.8
• https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.2
• https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-88vh-gx85-p36m

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