CVE-2026-66071Network attack vectorHinoki check available

Broker crash via OAuth2 scope atom exhaustion

Published Sep 25, 2026 · Updated Sep 25, 2026

Resource exhaustion in RabbitMQ Server allows remote authenticated users to crash the broker through crafted OAuth2 JWT scope tags. The extract_scopes/1 function passes each rabbitmq.tag scope value to rabbit_data_coercion:to_atom(), permanently adding a new Erlang atom for every novel tag. The OAuth2 backend must be enabled, and a trusted identity provider must issue signed tokens containing attacker-influenced scopes; repeated logins can exhaust the VM atom table and abort the broker.

CVSS severity6.0
Medium
EPSS probability0.47%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Resource exhaustion in RabbitMQ Server allows remote authenticated users to crash the broker through crafted OAuth2 JWT scope tags. The extract_scopes/1 function passes each rabbitmq.tag scope value to rabbit_data_coercion:to_atom(), permanently adding a new Erlang atom for every novel tag. The OAuth2 backend must be enabled, and a trusted identity provider must issue signed tokens containing attacker-influenced scopes; repeated logins can exhaust the VM atom table and abort the broker.

The record

CVE
CVE-2026-66071
Published
Sep 25, 2026
Updated
Sep 25, 2026
Vendor
RabbitMQ
Product
RabbitMQ Server
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 3.13.0, < 3.13.15
  2. Affected versionversion=>= 4.0.0, < 4.0.22
  3. Affected versionversion=>= 4.1.0, < 4.1.11
  4. Affected versionversion=>= 4.2.0, < 4.2.6
  5. Affected versionversion=>= 4.3.0, < 4.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

RabbitMQ · RabbitMQ Serverversion=>= 3.13.0, < 3.13.15; version=>= 4.0.0, < 4.0.22; version=>= 4.1.0, < 4.1.11; version=>= 4.2.0, < 4.2.6; version=>= 4.3.0, < 4.3.1

Published CVSS scores

6.0RabbitMQ GitHub Security AdvisoryCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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