Improper Certificate Validation Affecting rabbitmq-server package, versions <3.6.10-1ubuntu0.5+esm1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.23% (13th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-UBUNTU1804-RABBITMQSERVER-20126230
  • published18 Oct 2026
  • disclosed23 Sept 2026

Introduced: 23 Sep 2026

CVE-2026-67231  (opens in a new tab)
CWE-295  (opens in a new tab)

How to fix?

Upgrade Ubuntu:18.04 rabbitmq-server to version 3.6.10-1ubuntu0.5+esm1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream rabbitmq-server package and not the rabbitmq-server package as distributed by Ubuntu. See How to fix? for Ubuntu:18.04 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1