CVE-2026-67240: RabbitMQ is a messaging and streaming broker

Routine

MEDIUM 6.5UPGRADE

CVE-2026-67240 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. Prior to versions 4.2.7 and 4.3.1, pattern_to_regex maps % -> .*? and _ -> ., then compiles ^...$ with only [unicode]; re:run is called with only [{capture, none}] - no explicit match_limit. A pattern like %_%_..._%X becomes ^.*?..*?.....*?.X$ with overlapping lazy quantifiers. The whole-expression cap is ?MAX_EXPRESSION_LENGTH=4096 chars / ?MAX_TOKENS=200; a LIKE string literal is one token, so ~2000

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 74%)
CISA exploited list	No
Weakness	CWE-1333
Published	2026-09-23
Last modified	2026-10-30

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

Last updated 2026-10-30 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-23 21:17 UTCPublished CVE record published
2026-10-30 18:17 UTCUpdated Record last modified

broadcom rabbitmq server UPGRADE

Affected: >= 4.2.0 and < 4.2.7 · >= 4.3.0 and < 4.3.1

Fixed in: 4.2.7, 4.3.1

Safe to downgrade to: a release before 4.2.0

1. Check installed version

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

2. UPGRADE to 4.2.7 (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 4.2.0 (Debian / Ubuntu)

apt-cache madison rabbitmq-server sudo apt install rabbitmq-server=<VERSION_BEFORE_4.2.0> 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_4.2.0> 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-2026-67240?

rabbitmq server: upgrade to 4.2.7, 4.3.1. Exact commands for each OS are on this page.

Is CVE-2026-67240 being exploited?

CVE-2026-67240 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-2026-67240 affect?

CVE-2026-67240 affects rabbitmq server. Severity is medium (CVSS 6.5). RabbitMQ is a messaging and streaming broker. Prior to versions 4.2.7 and 4.3.1, pattern_to_regex maps % -> .*? and _ -> ., then compiles ^...$ with only [unicode]; re:run is called with only [{capture, none}] - no explicit match_limit. A p

How urgent is CVE-2026-67240?

Priority 29/100. No elevated risk signals yet.

Software pages

RabbitMQ vulnerabilities

Related CVEs

CVE-2026-67228 MEDIUM 4.9 UPGRADE RabbitMQ is a messaging and streaming broker
CVE-2026-66069 MEDIUM 4.3 UPGRADE RabbitMQ is a messaging and streaming broker
CVE-2026-66067 MEDIUM 6.5 UPGRADE RabbitMQ is a messaging and streaming broker
CVE-2026-67238 MEDIUM 6.5 UPGRADE RabbitMQ is a messaging and streaming broker
CVE-2026-44838 HIGH 8.1 UPGRADE RabbitMQ is a messaging and streaming broker

References

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