CVE-2026-67231: RabbitMQ: Trust-store whitelist by Issuer+Serial only

Severity: critical (CVSS 9.1 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: none known
Published: 2026-09-23 · updated 2026-10-19
Weakness: CWE-295

Description

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.

Affected products

rabbitmq-server: from 3.13.0 before 3.13.15; from 4.0.0 before 4.0.20; from 4.1.0 before 4.1.11; from 4.2.0 before 4.2.6 — fixed in 3.13.15, 4.0.20, 4.1.11, 4.2.6

How to fix

Upgrade to a fixed version: rabbitmq-server 3.13.15, 4.0.20, 4.1.11, 4.2.6. Check the vendor advisory for mitigations.

References

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