Medium severity · published Sep 25, 2026
CVE-2026-67226
RabbitMQ: Admin-only atom exhaustion: PUT /api/users tags list
4.9
CVSS
0.4%
EPSS
No
On KEV
Description
RabbitMQ is a messaging and streaming broker. From 4.0.0 until 4.0.22 and 4.1.14 and 4.2.7, Admin-only atom exhaustion: PUT /api/users tags list. settags/2 maps rabbitdatacoercion:toatom/1 over the user's tags list. The 20 MB management body limit fits ~3-4M short tag strings. An administrator can crash the node in a single request by creating a user (or importing definitions) with ~1M unique tag administrator. This issue is fixed in versions 4.0.22 and 4.1.14 and 4.2.7.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 33% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RA
rabbitmq-server · rabbitmq
>= 4.0.0, < 4.0.22; >= 4.1.0, < 4.1.14; >= 4.2.0, < 4.2.7 · source: vendor
RS
Rabbitmq Server · Broadcom
4.0.0 before 4.0.22; 4.1.0 before 4.1.14; 4.2.0 before 4.2.7 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-67226
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-67226
Patch
https://github.com/rabbitmq/rabbitmq-server/commit/86601c5a6d1c7e41060e3dbd165c88bdc91266ee
Release Notes
https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.7
Vendor Advisory
https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-34c7-r8w9-5wv8
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