CVE-2026-67231: RabbitMQ is a messaging and streaming broker.

RabbitMQ is a messaging and streaming broker.

RabbitMQ is a messaging and streaming broker. Prior to versions 3.13.15, 4.0.20, 4.1.11, 4.2.6, and 4.3.0, The trust-store plugin installs a verify_fun that overrides {bad_cert, unknown_ca} / {bad_cert, selfsigned_peer} when the presented cert "matches" a whitelisted one. The match key is extract_issuer_id/1 → public_key:pkix_issuer_id/2 → {IssuerName, SerialNumber} , both fields are taken verbatim from the presented certificate body and contain no public-key, SKI, fingerprint or signature material. is_whitelisted/1 is a pure ets:member lookup; the stored full DER is used only for list/0 display and is never compared against the presented cert. cacerts is [], so the whitelisted cert is never used as a trust anchor for path validation either. TLS client-authentication bypass: an attacker who knows the issuer DN + serial of any whitelisted certificate can connect with a forged self-signed cert. Preconditions include rabbitmq_trust_store plugin enabled and used as the TLS verify_fun Attacker knows or can guess the {Issuer, Serial} of at least one whitelisted cert (non-secret; exposed via CLI/logs/any cert copy). This issue is fixed in versions 3.13.15, 4.0.20, 4.1.11, 4.2.6, and 4.3.0

Description from the National Vulnerability Database, published by GitHub

What it means for a small business

If your business uses rabbitmq-server, install the vendor's update. If you're not sure whether you use it, ask whoever manages your computers.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.23%, higher than 13% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

Check your own setup

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Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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