CVE-2026-66078: RabbitMQ is a messaging and streaming broker

Routine

MEDIUM 5.5UPGRADE

CVE-2026-66078 is a medium-severity flaw (CVSS 5.5) 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 4.0.20 and 4.1.11 and 4.2.6, protected tag bypass via bulk-delete. dELETE /api/users/:name refuses to delete users tagged protected (rabbitmgmtwmuser:deleteresource/2 checks isprotecteduser). POST /api/users/bulk-delete iterates the supplied username list and calls rabbitauthbackendinternal:deleteuser/2 directly , that function has no protected-tag check , so the guard is

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	0.4% (top 63%)
CISA exploited list	No
Weakness	CWE-862
Published	2026-09-25
Last modified	2026-10-15

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

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

Am I affected?

Timeline

2026-09-25 17:17 UTCPublished CVE record published
2026-10-15 20:07 UTCUpdated Record last modified

broadcom rabbitmq server UPGRADE

Affected: >= 3.13.0 and < 3.13.15 · >= 4.0.0 and < 4.0.20 · >= 4.1.0 and < 4.1.11 · >= 4.2.0 and < 4.2.6

Fixed in: 3.13.15, 4.0.20, 4.1.11, 4.2.6

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-2026-66078?

rabbitmq server: upgrade to 3.13.15, 4.0.20, 4.1.11, 4.2.6. Exact commands for each OS are on this page.

Is CVE-2026-66078 being exploited?

CVE-2026-66078 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-2026-66078 affect?

CVE-2026-66078 affects rabbitmq server. Severity is medium (CVSS 5.5). RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.15 and 4.0.20 and 4.1.11 and 4.2.6, protected tag bypass via bulk-delete. dELETE /api/users/:name refuses to delete users tagged protected (rabbitmgmtwmuser:deleteresource

How urgent is CVE-2026-66078?

Priority 34/100. Public exploit reference

Software pages

RabbitMQ vulnerabilities

Related CVEs

CVE-2026-44838 HIGH 8.1 UPGRADE RabbitMQ is a messaging and streaming broker
CVE-2026-44839 MEDIUM 4.8 UPGRADE RabbitMQ is a messaging and streaming broker
CVE-2026-57219 HIGH 7.5 UPGRADE RabbitMQ is a messaging and streaming broker
CVE-2026-57220 HIGH 7.5 UPGRADE RabbitMQ is a messaging and streaming broker
CVE-2026-57211 MEDIUM 6.5 UPGRADE RabbitMQ is a messaging and streaming broker

References

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