HighCVE-2026-67409

    Rabbitmq-server: Unchecked Return Value (CVE-2026-67409)

    Published Last modified Sources: Ubuntu, Red Hat, CVE.org, OSV, Msrc Update Guide, BSI

    What is affected, what to do

    A flaw was found in rabbitmq-server. When retrieving cryptographic signing keys from an identity provider's JSON Web Key Set (JWKS) endpoint, the server fails to validate HTTP response status codes.

    Update rabbitmq_server to version 4.1.14, RabbitMQ to version 4.3.3.

    Affected
    • Rabbitmq-server gte 3.13.0, < 3.13.18..*

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    8.2

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v4

    6.5

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: Ubuntu, Red Hat, CVE.org, OSV, Msrc Update Guide, BSI

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 36.1

    Show all metrics
    Severity
    High
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    80.20 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    8.2 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    6.5
    CVSS v4

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    8.2
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

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    0.4 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    36.1
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CISA assessment (SSVC)
    Exploitation: proof of concept · not automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 25 September 2026
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-252

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    A flaw was found in rabbitmq-server. When retrieving cryptographic signing keys from an identity provider's JSON Web Key Set (JWKS) endpoint, the server fails to validate HTTP response status codes. If an error response is returned with valid JSON lacking key data, all previously cached signing keys are purged. This allows an attacker to cause a persistent Denial of Service (DoS) by preventing all legitimate users from authenticating.

    Source: Ubuntu Security Notices, redhat_csaf, NVD (NIST), OSV (Open Source Vulnerabilities), cvelistv5, Microsoft Security Update Guide, BSI WID Portal, BSI CSAF

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    rabbitmqrabbitmq-server
    • ≥ 3.13.0, < 3.13.18
    • —
    broadcomrabbitmq_server
    • 4.1.0 – < 4.1.14
    • 4.0.0 – < 4.0.23
    • 4.3.0 – < 4.3.3
    • 4.2.0 – < 4.2.9
    • 3.13.0 – < 3.13.18
    • 4.1.14
    • 4.0.23
    • 4.3.3
    • 4.2.9
    • 3.13.18
    Open SourceRabbitMQ
    • < 4.3.3
    • < 4.0.24
    • < 4.1.14
    • < 3.13.18
    • < 4.2.9
    • 4.3.3
    • 4.0.24
    • 4.1.14
    • 3.13.18
    • 4.2.9

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxubunturabbitmq-serverbionic
    Linuxubunturabbitmq-serverfocal
    Linuxubunturabbitmq-serverjammy
    Linuxubunturabbitmq-servernoble
    Linuxubunturabbitmq-serverresolute
    Linuxubunturabbitmq-serverxenial

    Weakness classes (CWE)

    • CWE-252Unchecked Return Value

      Base

      The product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.

      Entry at MITRE CWE-252

    References & sources

    • github.comrabbitmq/rabbitmq-server/security/advisories/GHSA-qw3h-qqm9-jrw8x_refsource_CONFIRM
    • github.comrabbitmq/rabbitmq-server/releases/tag/v4.2.9x_refsource_MISC
    • github.comrabbitmq/rabbitmq-server/releases/tag/v4.3.3x_refsource_MISC
    • NVD (NIST)vuln/detail/CVE-2026-67409web

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Initial analysis by NVDNVD

      Newly listed as affected:
      • Broadcom RabbitMQ (4.1.0 – before 4.1.14; 4.2.0 – before 4.2.9; 4.3.0 – before 4.3.3; 4.0.0 – before 4.0.23; 3.13.0 – before 3.13.18)

      CVSS V3.1: AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      CVSSadded
      —
      AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
      Product configurationadded
      —
      OR *cpe:2.3:a:broadcom:rabbitmq_server:*:*:*:*:*:*:*:* versions from (including) 4.1.0 up to (excluding) 4.1.14 *cpe:2.3:a:broadcom:rabbitmq_server:*:*:*:*:*:*:*:* versions from (including) 4.2.0 up to (excluding) 4.2.9 *cpe:2.3:a:broadcom:rabbitmq_server:*:*:*:*:*:*:*:* versions from (including) 4.3.0 up to (excluding) 4.3.3 *cpe:2.3:a:broadcom:rabbitmq_server:*:*:*:*:*:*:*:* versions from (including) 4.0.0 up to (excluding) 4.0.23 *cpe:2.3:a:broadcom:rabbitmq_server:*:*:*:*:*:*:*:* versions from (including) 3.13.0 up to (excluding) 3.13.18
      Reference typeadded
      —
      GitHub, Inc.: https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.9 Types: Release Notes
      Reference typeadded
      —
      GitHub, Inc.: https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.3 Types: Release Notes
      Reference typeadded
      —
      CISA-ADP: https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-qw3h-qqm9-jrw8 Types: Exploit, Third Party Advisory
      Reference typeadded
      —
      GitHub, Inc.: https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-qw3h-qqm9-jrw8 Types: Exploit, Third Party Advisory

      Source identifier: nvd@nist.gov

    2. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: proof of concept, automatable: no

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-qw3h-qqm9-jrw8
      SSVC assessmentadded
      —
      {"id":"CVE-2026-67409","role":"CISA Coordinator","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-25T17:49:17.770463Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    3. ReceivedGitHub

      CVSS V4.0: AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

      Weakness type: CWE-252

      Description added or changed

      Show 7 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      RabbitMQ is a messaging and streaming broker. From 3.13.0 until 4.3.3, 4.2.9, 4.1.14, 4.0.23, and 3.13.18, JWKS Fetch Ignores HTTP Response Status Code - Signing Key Destruction Causes Authentication DoS (CWE-252). the JWKS key fetching mechanism in uaajwt.erl does not validate the HTTP response status code when downloading signing keys from the OAuth2 provider's JWKS endpoint. Non-200 responses (including 4xx and 5xx errors) are processed identically to successful responses. When the JWKS endpoint returns an error response with a valid-JSON body that lacks a keys field, all previously cached signing keys are destroyed, causing a persistent authentication denial of Files: deps/rabbitmqauthbackendoauth2/src/uaajwt.erl, lines 50-63 deps/rabbitmqauthbackendoauth2/src/uaajwks.erl, lines 5-7 deps/rabbitmqauthbackendoauth2/src/rabbitoauth2provider.erl, lines 98-107 Bug 1: HTTP status code ignored (uaajwt.erl:50-63): The Erlang httpc module returns {ok, {{HttpVersion, StatusCode, ReasonPhrase}, Headers, Body}}. The pattern {ok, {, , JwksBody}} matches ANY successful HTTP transaction Persistent authentication DoS: Once keys are destroyed, ALL OAuth2/JWT authentication fails for all users until a new successful JWKS refresh occurs Amplification: A single attacker can deny access to all legitimate OAuth2 users across the entire RabbitMQ. This issue is fixed in versions 4.3.3, 4.2.9, 4.1.14, 4.0.23, and 3.13.18.
      CVSSadded
      —
      AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
      Weakness type (CWE)added
      —
      CWE-252
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/67xxx/CVE-2026-67409.json">CVE-2026-67409</a>
      Referenceadded
      —
      https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.9
      Referenceadded
      —
      https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.3
      Referenceadded
      —
      https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-qw3h-qqm9-jrw8

      Source identifier: security-advisories@github.com

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