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CVE-2026-66071: RabbitMQ is a messaging and streaming broker

39
Routine
MEDIUM 6.5UPGRADE

CVE-2026-66071 is a medium-severity flaw (CVSS 6.5) 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. From 3.13.0 until 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1, Atom exhaustion: OAuth2 JWT tag: scope values. extractscopes/1 parses scopes of the form .tag: and calls rabbitdatacoercion:toatom() to convert to a tag atom. The token signature is verified first, so the attacker cannot forge scopes , but in IdP configurations where scope content is user-influenced, each login with a novel tag value

Why this priority

  • Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score6.5 (Medium)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededLow
User interactionNone
EPSS exploit chance0.5% (top 55%)
CISA exploited listNo
WeaknessCWE-400
Published2026-09-25
Last modified2026-10-15
Publisher (CNA): GitHub, Inc. · Vendor: broadcom

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Last updated 2026-10-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

broadcom rabbitmq server UPGRADE
Affected: >= 3.13.0 and < 3.13.15 · >= 4.0.0 and < 4.0.22 · >= 4.1.0 and < 4.1.11 · >= 4.2.0 and < 4.2.6 · >= 4.3.0 and < 4.3.1
Fixed in: 3.13.15, 4.0.22, 4.1.11, 4.2.6, 4.3.1
Safe to downgrade to: a release before 3.13.0
1. Check installed version
apt-cache policy rabbitmq-server || rpm -q rabbitmq-server || rabbitmq-server --version
2. UPGRADE to 3.13.15 (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 3.13.0 (Debian / Ubuntu)
apt-cache madison rabbitmq-server sudo apt install rabbitmq-server=<VERSION_BEFORE_3.13.0> 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_3.13.0> 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-2026-66071?

rabbitmq server: upgrade to 3.13.15, 4.0.22, 4.1.11, 4.2.6, 4.3.1. Exact commands for each OS are on this page.

Is CVE-2026-66071 being exploited?

CVE-2026-66071 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-2026-66071 affect?

CVE-2026-66071 affects rabbitmq server. Severity is medium (CVSS 6.5). RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1, Atom exhaustion: OAuth2 JWT tag: scope values. extractscopes/1 parses scopes of the form .tag: and calls rabbitdatacoercion:t

How urgent is CVE-2026-66071?

Priority 39/100. Public exploit reference

Software pages

RabbitMQ vulnerabilities

Related CVEs

References

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