Vulnerability-Lookup

RHSA-2026:42387

Vulnerability from csaf_redhat - Published: 2026-07-21 01:28 - Updated: 2026-08-02 19:13

Summary

Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

Severity

Important

Notes

Topic: An update for Red Hat Hardened Images RPMs is now available.

Details: This update includes the following RPMs: rabbitmq-server4.2: * rabbitmq-server4.2-4.2.9-0.1.hum1 (aarch64, x86_64) * rabbitmq-server4.2-4.2.9-0.1.hum1.src (src)

Terms of Use: This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.

CVE-2026-44838

A flaw was found in RabbitMQ. An authenticated MQTT (Message Queuing Telemetry Transport) user can bypass topic-level authorization by injecting regular expression operators. This occurs because the client ID, provided by the user in the MQTT CONNECT packet, is inserted into authorization regex patterns without proper escaping of special characters. This vulnerability allows an attacker to gain unauthorized access to topics.

8.1 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

CWE-624 - Executable Regular Expression Error

Affected products

Fixed 3 products

Product	Version	Remediation
Unresolved product id: Red Hat Hardened Images:rabbitmq-server4-2-main@aarch64	—	Vendor Fix fix
Unresolved product id: Red Hat Hardened Images:rabbitmq-server4-2-main@src	—	Vendor Fix fix
Unresolved product id: Red Hat Hardened Images:rabbitmq-server4-2-main@x86_64	—	Vendor Fix fix

Threats

Impact Important

References

10 references

URL	Category
https://access.redhat.com/errata/RHSA-2026:42387	self
https://images.redhat.com/	external
https://access.redhat.com/security/cve/CVE-2026-44838	external
https://access.redhat.com/security/updates/classi…	external
https://security.access.redhat.com/data/csaf/v2/a…	self
https://access.redhat.com/security/cve/CVE-2026-44838	self
https://bugzilla.redhat.com/show_bug.cgi?id=2482208	external
https://www.cve.org/CVERecord?id=CVE-2026-44838	external
https://nvd.nist.gov/vuln/detail/CVE-2026-44838	external
https://github.com/rabbitmq/rabbitmq-server/secur…	external

JSON

To clipboard

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        "text": "This update includes the following RPMs:\n\nrabbitmq-server4.2:\n  * rabbitmq-server4.2-4.2.9-0.1.hum1 (aarch64, x86_64)\n  * rabbitmq-server4.2-4.2.9-0.1.hum1.src (src)",
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  "vulnerabilities": [
    {
      "cve": "CVE-2026-44838",
      "cwe": {
        "id": "CWE-624",
        "name": "Executable Regular Expression Error"
      },
      "discovery_date": "2026-05-27T16:01:31.763532+00:00",
      "ids": [
        {
          "system_name": "Red Hat Bugzilla ID",
          "text": "2482208"
        }
      ],
      "notes": [
        {
          "category": "description",
          "text": "A flaw was found in RabbitMQ. An authenticated MQTT (Message Queuing Telemetry Transport) user can bypass topic-level authorization by injecting regular expression operators. This occurs because the client ID, provided by the user in the MQTT CONNECT packet, is inserted into authorization regex patterns without proper escaping of special characters. This vulnerability allows an attacker to gain unauthorized access to topics.",
          "title": "Vulnerability description"
        },
        {
          "category": "summary",
          "text": "rabbitmq-server: RabbitMQ: Authorization bypass via regular expression injection in MQTT client ID",
          "title": "Vulnerability summary"
        },
        {
          "category": "other",
          "text": "Important: An authorization bypass flaw in the RabbitMQ MQTT plugin allows an authenticated user to inject regular expression operators into the client ID, circumventing topic-level access controls. This could lead to unauthorized access to sensitive topics.",
          "title": "Statement"
        },
        {
          "category": "general",
          "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product\u0027s status, and are included for informational purposes to better understand the severity of this vulnerability.",
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        }
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        },
        {
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          ],
          "restart_required": {
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        }
      ],
      "scores": [
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            "availabilityImpact": "NONE",
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
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      "title": "rabbitmq-server: RabbitMQ: Authorization bypass via regular expression injection in MQTT client ID"
    }
  ]
}

CVE-2026-44838 (GCVE-0-2026-44838)

Vulnerability from cvelistv5 – Published: 2026-05-27 15:03 – Updated: 2026-05-28 14:31

Title

RabbitMQ MQTT Topic Permission Authorization Bypass

Summary

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.

Severity

5.3 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:H/SI:H/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-863 - Incorrect Authorization

Assigner

GitHub_M

References

1 reference

URL	Tags
https://github.com/rabbitmq/rabbitmq-server/secur…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
rabbitmq	rabbitmq-server	Affected: >= 4.2.0, < 4.2.4

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-44838",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-28T14:30:53.473259Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-28T14:31:11.075Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "rabbitmq-server",
          "vendor": "rabbitmq",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.2.0, \u003c 4.2.4"
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      ],
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          "lang": "en",
          "value": "RabbitMQ is a messaging and streaming broker. From 4.2.0 to before 4.2.4, RabbitMQ\u0027s 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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "LOW",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "HIGH",
            "subIntegrityImpact": "HIGH",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:H/SI:H/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
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          "descriptions": [
            {
              "cweId": "CWE-863",
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              "lang": "en",
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            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-27T15:03:57.467Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-x866-xp2g-cx8v",
          "tags": [
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          ],
          "url": "https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-x866-xp2g-cx8v"
        }
      ],
      "source": {
        "advisory": "GHSA-x866-xp2g-cx8v",
        "discovery": "UNKNOWN"
      },
      "title": "RabbitMQ MQTT Topic Permission Authorization Bypass"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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    "datePublished": "2026-05-27T15:03:57.467Z",
    "dateReserved": "2026-05-07T21:21:48.352Z",
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    "state": "PUBLISHED"
  },
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

RHSA-2026:42387

CVE-2026-44838 (GCVE-0-2026-44838)

Tags

Sightings

Nomenclature