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CVE-2026-66079: RabbitMQ is a messaging and streaming broker

37
Routine
HIGH 7.5REMOTEUPGRADE

CVE-2026-66079 is a high-severity flaw (CVSS 7.5) 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. Prior to versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6, parse_array_primitive/2 for constructor 0x45 (list0) returns an element with byte-width B = 0. The enclosing array32 parser at line 148 reads a 4-byte Count from the wire and loops Count times consuming B bytes each , with B = 0, no input is consumed and the loop builds a list of Count empty elements bounded only by the 32-bit field. The SASL-mecha

Why this priority

  • High severity
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score7.5 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance0.3% (top 75%)
CISA exploited listNo
WeaknessCWE-770
Published2026-09-23
Last modified2026-10-19
Publisher (CNA): GitHub, Inc. · Vendor: broadcom

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Last updated 2026-10-19 · 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 < 4.0.20 · >= 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-2026-66079?

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-2026-66079 being exploited?

CVE-2026-66079 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-2026-66079 affect?

CVE-2026-66079 affects rabbitmq server. Severity is high (CVSS 7.5). RabbitMQ is a messaging and streaming broker. Prior to versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6, parse_array_primitive/2 for constructor 0x45 (list0) returns an element with byte-width B = 0. The enclosing array32 parser at line 148 read

How urgent is CVE-2026-66079?

Priority 37/100. High severity; Remotely exploitable, no login, no user action

Software pages

RabbitMQ vulnerabilities

Related CVEs

References

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