CVE-2026-66080: RabbitMQ is a messaging and streaming broker

Routine

MEDIUM 4.9UPGRADE

CVE-2026-66080 is a medium-severity flaw (CVSS 4.9) affecting rabbitmq server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.9 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-770
Published	2026-09-23
Last modified	2026-10-19

Publisher (CNA): GitHub, Inc. · Vendor: broadcom

Last updated 2026-10-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-23 21:16 UTCPublished CVE record published
2026-10-19 20:37 UTCUpdated Record last modified

broadcom rabbitmq server UPGRADE

Affected: >= 4.1.0 and < 4.1.11 · >= 4.2.0 and < 4.2.6

Fixed in: 4.1.11, 4.2.6

Safe to downgrade to: a release before 4.1.0

1. Check installed version

apt-cache policy rabbitmq-server || rpm -q rabbitmq-server || rabbitmq-server --version

2. UPGRADE to 4.1.11 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade rabbitmq-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade rabbitmq-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.1.0 (Debian / Ubuntu)

apt-cache madison rabbitmq-server sudo apt install rabbitmq-server=<VERSION_BEFORE_4.1.0> sudo apt-mark hold rabbitmq-server

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list rabbitmq-server sudo dnf downgrade rabbitmq-server-<VERSION_BEFORE_4.1.0> sudo dnf versionlock add rabbitmq-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-66080?

rabbitmq server: upgrade to 4.1.11, 4.2.6. Exact commands for each OS are on this page.

Is CVE-2026-66080 being exploited?

CVE-2026-66080 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-66080 affect?

CVE-2026-66080 affects rabbitmq server. Severity is medium (CVSS 4.9). 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) a

How urgent is CVE-2026-66080?

Priority 23/100. No elevated risk signals yet.

Software pages

RabbitMQ vulnerabilities

Related CVEs

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References

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