CVE-2026-67226

RabbitMQ: Admin-only atom exhaustion: PUT /api/users tags list

MEDIUM
4.9
CVSS Score
Published: September 25, 2026 at 04:29 PM UTC
Updated: October 20, 2026 at 01:36 PM UTC
2 products affected across 2 vendorsRabbitmq ServerRabbitmq Server

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Severity
MEDIUM4.9
Exploit prediction
EPSS 0.4%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

4.0.0 ≤ v < 4.0.224.1.0 ≤ v < 4.1.144.2.0 ≤ v < 4.2.7
Affected range stops below 4.0.22, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.1.14, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.2.7, so it looks safe — our inference, not a vendor statement

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-400

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