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No exploitation reportedFix available

CVE-2026-66071

No exploitation reported by the sources we read.

  • Published2026-09-25
  • Fixed in4.3.1 · 4.2.6 · 4.1.11 · 4.0.22 · 3.13.15
  • WeaknessCWE-400

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1, Atom exhaustion: OAuth2 JWT tag: scope values. extractscopes/1 parses scopes of the form .tag: and calls rabbitdatacoercion:toatom() to convert to a tag atom. The token signature is verified first, so the attacker cannot forge scopes , but in IdP configurations where scope content is user-influenced, each login with a novel tag value leaks one In deployments where users can influence the scopes included in their IdP-issued JWT rabbitmqauthbackendoauth2 enabled IdP permits attacker-influenced scope values in signed tokens. This issue is fixed in versions 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1.

Timeline

dates in UTC
  1. 2026-09-2517:17CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-66071?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-66071?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Broadcom rabbitmq server
BranchAffectedFixed in
4.3≥ 4.3.0, < 4.3.14.3.1
4.2≥ 4.2.0, < 4.2.64.2.6
4.1≥ 4.1.0, < 4.1.114.1.11
4.0≥ 4.0.0, < 4.0.224.0.22
3.13≥ 3.13.0, < 3.13.153.13.15

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2026-66071 Red Hat Product Security3 products fixed · 8 known affected

    rabbitmq-server: rabbitmq-server: Denial of service via atom exhaustion in OAuth2 JWT scope parsing

    rabbitmq-server4.2.src as a component of Red Hat Hardened Images · rabbitmq-server as a component of Red Hat OpenStack Platform 13 (Queens) · rabbitmq-server.src as a component of Red Hat OpenStack Platform 13 (Queens) · +5 more

  • RHSA-2026:67552 Red Hat Product Security3 products fixed

    Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

Full record on NVD

Fix

  1. Update Broadcom rabbitmq server to 4.3.1 · 4.2.6 · 4.1.11 · 4.0.22 · 3.13.15
  2. Vendor fix Red Hat Product Security CVE-2026-66071 · 3 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
  3. No fix available, says the vendor Red Hat Product Security CVE-2026-66071 · 1 productFix deferred
  4. No fix planned, says the vendor Red Hat Product Security CVE-2026-66071 · 6 productsOut of support scope
  5. No fix planned, says the vendor Red Hat Product Security CVE-2026-66071 · 1 productWill not fix

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionnone2026-09-25
  • OpenCVESSVC decisionnone—
  • CNACVSS 4.06read 2026-10-23
  • NVDCVSS 3.16.5read 2026-10-23
  • CNAweakness (CWE)CWE-400read 2026-10-23
  • FIRST EPSSEPSS score0.5 %2026-10-22
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS 4.0 vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/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
Published
2026-09-25
Last Modified
2026-10-15
NVD status
Analyzed

Frequently asked questions

What is CVE-2026-66071?

RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1, Atom exhaustion: OAuth2 JWT tag: scope values. extractscopes/1 parses scopes of the form .tag: and calls rabbitdatacoercion:toatom() to convert to a tag atom. The token signature is verified first, so the attacker cannot forge scopes , but in IdP configurations where scope content is user-influenced, each login with a novel tag value leaks one In deployments where users can influence the scopes included in their IdP-issued JWT rabbitmqauthbackendoauth2 enabled IdP permits attacker-influenced scope values in signed tokens. This issue is fixed in versions 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1.

Is CVE-2026-66071 actively exploited?

Active exploitation of CVE-2026-66071 has not been confirmed. Its EPSS score was 0.5% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-66071?

CVE-2026-66071 has a CVSS v3 base score of 6.5 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

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