CVE-2026-66077: RabbitMQ is a messaging and streaming broker

Q: How urgent is CVE-2026-66077?

Priority 22/100. No elevated risk signals yet.

Routine

MEDIUM 6.1UPGRADE

CVE-2026-66077 is a medium-severity flaw (CVSS 6.1) 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 3.13.15, 4.0.20, 4.1.11, and 4.2.6, The management UI uses EJS 1.0 in which <%= ... %> does NOT HTML-escape. connection.ejs:135 renders <%= connection.ssl_details.peer_cert_subject %> (and peer_cert_issuer) directly into the page. The same pattern appears in streamConnection.ejs:102,106,110. The values come from rabbit_ssl:peer_cert_subject/1 which formats the DN as a string without

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 96%)
CISA exploited list	No
Weakness	CWE-79
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: >= 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-2026-66077?

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-2026-66077 being exploited?

CVE-2026-66077 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-2026-66077 affect?

CVE-2026-66077 affects rabbitmq server. Severity is medium (CVSS 6.1). RabbitMQ is a messaging and streaming broker. Prior to versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6, The management UI uses EJS 1.0 in which <%= ... %> does NOT HTML-escape. connection.ejs:135 renders <%= connection.ssl_details.peer_cert_sub

How urgent is CVE-2026-66077?

Priority 22/100. No elevated risk signals yet.

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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