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CVE-2026-67409: RabbitMQ: JWKS Fetch Ignores HTTP Response Status Code - Signing Key Destruction Causes Authentication DoS

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-25 · updated 2026-10-08
• Weakness: CWE-252

Description

RabbitMQ is a messaging and streaming broker. From 3.13.0 until 4.3.3, 4.2.9, 4.1.14, 4.0.23, and 3.13.18, JWKS Fetch Ignores HTTP Response Status Code - Signing Key Destruction Causes Authentication DoS (CWE-252). the JWKS key fetching mechanism in uaajwt.erl does not validate the HTTP response status code when downloading signing keys from the OAuth2 provider's JWKS endpoint. Non-200 responses (including 4xx and 5xx errors) are processed identically to successful responses. When the JWKS endpoint returns an error response with a valid-JSON body that lacks a keys field, all previously cached signing keys are destroyed, causing a persistent authentication denial of Files: deps/rabbitmqauthbackendoauth2/src/uaajwt.erl, lines 50-63 deps/rabbitmqauthbackendoauth2/src/uaajwks.erl, lines 5-7 deps/rabbitmqauthbackendoauth2/src/rabbitoauth2provider.erl, lines 98-107 Bug 1: HTTP status code ignored (uaajwt.erl:50-63): The Erlang httpc module returns {ok, {{HttpVersion, StatusCode, ReasonPhrase}, Headers, Body}}. The pattern {ok, {, , JwksBody}} matches ANY successful HTTP transaction Persistent authentication DoS: Once keys are destroyed, ALL OAuth2/JWT authentication fails for all users until a new successful JWKS refresh occurs Amplification: A single attacker can deny access to all legitimate OAuth2 users across the entire RabbitMQ. This issue is fixed in versions 4.3.3, 4.2.9, 4.1.14, 4.0.23, and 3.13.18.

Affected products

• rabbitmq-server: from 3.13.0 before 3.13.18; from 4.0.0 before 4.0.23; from 4.1.0 before 4.1.14; from 4.2.0 before 4.2.9; from 4.3.0 before 4.3.3 — fixed in 3.13.18, 4.0.23, 4.1.14, 4.2.9, 4.3.3

How to fix

Upgrade to a fixed version: rabbitmq-server 3.13.18, 4.0.23, 4.1.14, 4.2.9. Check the vendor advisory for mitigations.

References

• https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.9
• https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.3
• https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-qw3h-qqm9-jrw8
• https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-qw3h-qqm9-jrw8

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