CVE-2026-67421

MEDIUMPre-NVD 4.54.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (20th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
4.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 4.5Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.19, 4.0.24, 4.1.15, 4.2.10, and 4.3.5, RabbitMQ Management rendered an AMQP authorization-error reason containing an attacker-controlled queue name as HTML when the OAuth management UI was enabled. Exploitation requires an attacker with queue configure permission, a management administrator who can see but cannot read that queue, and the administrator clicking Get Message(s). A queue name containing a base element can then retarget the automatic relative refresh because the Content Security Policy omits base-uri and connect-src, and an attacker endpoint that permits the management origin through CORS can receive the victim's Authorization header. This issue is fixed in versions 3.13.19, 4.0.24, 4.1.15, 4.2.10, and 4.3.5.

CVSS v3
4.5
EG Score
4.5MEDIUMmedium confidence
EG Risk
36
EG Risk 36/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity45% × 45%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
20th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 25, 2026

Last Modified

September 28, 2026

Advisory Details (3)

Auto-updated Sep 25, 2026
Patch available. Sources: github_commit, github_release, github.
github_release Patch Available

RabbitMQ 4.3.5

Patch available: rabbitmq/rabbitmq-server v4.3.5

https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.5
github_commit

commit ff595eaaa6d4 (rabbitmq/rabbitmq-server)

Fix landed in rabbitmq/rabbitmq-server commit ff595eaaa6d4 — awaiting tagged release

https://github.com/rabbitmq/rabbitmq-server/commit/ff595eaaa6d4f580f72fa04801ffd35f48c46027
github Patch Available

Stored HTML Injection in RabbitMQ Management OAuth Error Handling · Advisory · rabbitmq/rabbitmq-server · GitHub

https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-6256-27fm-4rgr

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-04 01:41 UTCEG score recompute
  2. 2026-10-03 14:26 UTCEPSS rescore
  3. 2026-10-02 23:30 UTCEG score recompute
  4. 2026-10-02 17:56 UTCEPSS rescore
  5. 2026-10-01 21:19 UTCEG score recompute
  6. 2026-10-01 19:50 UTCEPSS rescore
  7. 2026-09-30 19:05 UTCEG score recompute
  8. 2026-09-30 15:03 UTCEPSS rescore
  9. 2026-09-29 16:55 UTCEG score recompute
  10. 2026-09-28 14:44 UTCEG score recompute
  11. 2026-09-28 13:52 UTCEPSS rescore
  12. 2026-09-28 01:00 UTCEG score recompute
  13. 2026-09-27 13:48 UTCEPSS rescore
  14. 2026-09-26 22:49 UTCEG score recompute
  15. 2026-09-26 15:59 UTCEPSS rescore
  16. 2026-09-25 20:39 UTCEG score recompute
  17. 2026-09-25 20:08 UTCEG score recompute
  18. 2026-09-25 17:33 UTCEG score recompute
  19. 2026-09-25 16:49 UTCEG score recompute
  20. 2026-09-25 16:49 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-67421?
CVE-2026-67421 is a medium vulnerability published on September 25, 2026. RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.19, 4.0.24, 4.1.15, 4.2.10, and 4.3.5, RabbitMQ Management rendered an AMQP authorization-error reason containing an attacker-controlled queue name as HTML when the OAuth management UI was enabled. Exploitation requires an…
When was CVE-2026-67421 disclosed?
CVE-2026-67421 was first published on September 25, 2026, with the most recent update on September 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-67421 actively exploited?
CVE-2026-67421 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (20th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-67421?
CVE-2026-67421 has a CVSS base score of 4.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-67421?
A fix for CVE-2026-67421 is available: update to the fixed version the vendor names in its advisory.

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