How severe is CVE-2026-44838?

CVE-2026-44838 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-44838 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-44838?

CVE-2026-44838 affects Broadcom Rabbitmq Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-44838?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-44838 have an EU (EUVD) identifier?

Yes. CVE-2026-44838 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32548.

When was CVE-2026-44838 published?

CVE-2026-44838 was published on 2026-05-27 and last updated on 2026-06-17.

CVE-2026-44838

CVE-2026-44838 is a high-severity vulnerability in Broadcom Rabbitmq Server with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v4: 5.3
EPSS exploit prediction: 0% (16th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-32548
Weakness: CWE-863
Affected product: Broadcom Rabbitmq Server
Published: 2026-05-27
Last modified: 2026-06-17

Description

RabbitMQ is a messaging and streaming broker. From 4.2.0 to before 4.2.4, RabbitMQ's MQTT plugin allows for topic-level authorization using regular expressions with variable substitution. Administrators can create patterns such as ^{client_id}-sensors$ to restrict user access to topics that include their client ID. However, the client_id is provided by the user in the MQTT CONNECT packet and is inserted into the regex pattern without escaping special regex characters. This flaw enables an authenticated MQTT user to inject regex operators to bypass authorization. This vulnerability is fixed in 4.2.4 and 4.3.0.

Frequently asked questions

What is CVE-2026-44838?: RabbitMQ is a messaging and streaming broker. From 4.2.0 to before 4.2.4, RabbitMQ's MQTT plugin allows for topic-level authorization using regular expressions with variable substitution. Administrators can create patterns such as ^{client_id}-sensors$ to restrict user access to topics that include their client ID. However, the client_id is provided by the user in the MQTT CONNECT packet and is inserted into the regex pattern without escaping special regex characters. This flaw enables an authenticated MQTT user to inject regex operators to bypass authorization. This vulnerability is fixed in 4.2.4 and 4.3.0.
How severe is CVE-2026-44838?: CVE-2026-44838 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-44838 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-44838?: CVE-2026-44838 affects Broadcom Rabbitmq Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-44838?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-44838 have an EU (EUVD) identifier?: Yes. CVE-2026-44838 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32548.
When was CVE-2026-44838 published?: CVE-2026-44838 was published on 2026-05-27 and last updated on 2026-06-17.

References

https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-x866-xp2g-cx8v

Affected products (1)

cpe:2.3:a:broadcom:rabbitmq_server:*:*:*:*:*:*:*:*

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