9.1

CVE-2026-67231: rabbitmq rabbitmq-server Improper Certificate Validation

CVSS: 9.1v4.0CriticalUndergoing analysis
AliasesUBUNTU-CVE-2026-67231DEBIAN-CVE-2026-67231
Published 23-09-2026Last modified 29-09-2026
Open JSON

Vulnerability summary

CVE-2026-67231 is a critical (CVSS 9.1) Improper Certificate Validation vulnerability in rabbitmq rabbitmq-server. EPSS estimates a 0.25% chance of exploitation in the next 30 days, higher than 15.1% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.1/10
010
Critical · v4.0 (CVE.org)
EPSS score
0.25%
0%100%
Low · Change unavailable
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
USN-8933-1

Timeline

  1. 23-09-2026
    PublishedVulnerability first disclosed.
  2. 29-09-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.25%

Chance of exploitation in the next 30 days

Percentile

15%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

24-09-202619-10-2026
EPSS score
0.25%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Debian1 product
  • rabbitmq-serverAll versions (No fix recorded) | < 4.3.0-2
Rabbitmq1 product
  • rabbitmq-server≥ 3.13.0, < 3.13.15 | ≥ 4.0.0, < 4.0.20 | ≥ 4.1.0, < 4.1.11 | ≥ 4.2.0, < 4.2.6
Ubuntu1 product
  • rabbitmq-serverAll versions (No fix recorded) | < 3.5.7-1ubuntu0.16.04.4+esm3 | < 3.6.10-1ubuntu0.5+esm1 | < 3.8.3-0ubuntu0.3+esm2 | < 3.9.27-0ubuntu0.6 | < 3.12.1-1ubuntu1.7 | < 4.0.5-10ubuntu5.2

3 vendors · 3 products

References

7 links