What’s Vulnerable › Vulnerabilities

CVE-2026-67419: RabbitMQ: Consecutive topic wildcards cause combinatorial routing work

• 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 2026-10-16
• Weakness: CWE-407

Description

RabbitMQ is a messaging and streaming broker. Prior to 4.3.5, an authenticated user who can bind a queue to a topic exchange and publish to it can use consecutive # segments in a binding key to make both topic matchers revisit the same trie-node and routing-key-suffix states without memoization. The matcher materializes duplicate destinations before deduplication, causing combinatorial CPU work and memory pressure that can disrupt routing for all tenants. This vulnerability is fixed in 4.3.5.

Affected products

• rabbitmq-server: from 4.3.0 before 4.3.5 — fixed in 4.3.5

How to fix

Upgrade to a fixed version: rabbitmq-server 4.3.5. Check the vendor advisory for mitigations.

References

• https://github.com/rabbitmq/rabbitmq-server/commit/c5ed7c4e97e02be688730803604cc7a88dbe4864
• https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.5
• https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-h964-v5mf-22cq
• https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-h964-v5mf-22cq

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