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GHSA-5F42-97GR-VFHQ

Vulnerability from github – Published: 2026-09-23 16:11 – Updated: 2026-09-23 16:11

Summary

Moquette: Pattern-ACL wildcard injection (cross-tenant authorization bypass) plus a remote-unauthenticated DoS cluster, a Will-message authorization bypass, and a cross-session durable-corruption bug

Details

moquette is reachable by untrusted MQTT clients (anonymous by default), so every byte from any client, including pre-authentication, is untrusted. This is a memory-safe JVM: the ceiling is authorization/ACL bypass + denial of service + cross-session integrity, not RCE (I did not find one and do not claim one). Audited at commit da7f719a6bab9829d520b5838e13ea7b1f9be3ef, module broker/.

What a connecting client can do

(Critical) Bypass pattern-based ACLs across tenants. In AuthorizationsCollector.canDoOperation (AuthorizationsCollector.java:116-131, esp. line 123) the clientId/username is substituted raw into a pattern ACL rule and then wildcard-matched, and the clientId is never validated for MQTT wildcard characters +/# at CONNECT (MQTTConnection.processConnect):

Topic substitutedTopic = new Topic(auth.topic.toString().replace("%c", client).replace("%u", username)); if (topic.match(substitutedTopic)) return true;

A client that connects with clientId + turns sensor/%c/# into the filter sensor/+/#, gaining cross-tenant read AND write. (Precondition: pattern ACL rules configured — a common multi-tenant setup.)

(High) Crash the whole broker. SessionEventLoop (SessionEventLoop.java:40-54) catches only InterruptedException and is never restarted (SessionEventLoopGroup), so any uncaught exception on it wedges every co-located client. Trivially reachable inputs: malformed $share/grp SUBSCRIBE (SharedSubscriptionUtils.extractShareName -> StringIndexOutOfBoundsException), deeply nested topic (CTrie recursion -> StackOverflowError), and ACL NPE below. Unbounded subscriptions / retained / in-flight / topic-alias / interceptor state (BrokerInterceptor uses an unbounded queue) also allow OOM; durable stores allow disk exhaustion.
(High) NPE in ACL sink on clientId # (invalid filter sensor/#/# -> null tokens -> Topic.match NPE at Topic.java:173).
(High) Will-message authorization bypass. Last-Will topic is published (PostOffice.publishWill) without canWrite/reserved-topic checks used for normal PUBLISH.
(Medium) Cross-session durable corruption. H2PersistentQueue opens queue_"+clientId and queue_"+clientId+"_meta; client id sensor_meta collides with victim sensor metadata map -> corrupts head/tail.
(Medium) Fail-open if authenticator/authorizator class fails to load -> PermitAll/AcceptAll (Server.java:483-531).

Proof of concept

Source-only, no network; PoCs run on JDK 17: - PoCPatternAcl — clientId + gains cross-tenant read/write; clientId # triggers NPE - PoCSharedSubCrash — extractShareName("$share/grp") throws StringIndexOutOfBoundsException - PoCMapCollision — H2 MVStore collision overwrites victim metadata pointer

Impact

Cross-tenant eavesdropping and injection, whole-broker DoS, unauthorized Will publishes, and cross-session durable corruption.

Remediation

Reject clientId/username containing +/# (and / if structural) at CONNECT; expand %c/%u as literal tokens.
Harden SessionEventLoop (catch Throwable + restart supervision) and validate $share filters.
Apply authorization to Will publishes like normal PUBLISH.
Add resource caps (connections, queues, retained, aliases, interceptor queue) + bounded session expiry.
Separate H2 namespaces and fail closed on auth-class load failure.

Severity

9.6 (Critical)


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

Show details on source website

JSON

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.18.0"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "io.moquette:moquette-broker"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.18.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-85724"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-23T16:11:18Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "moquette is reachable by untrusted MQTT clients (anonymous by default), so every byte from any client, including pre-authentication, is untrusted. This is a memory-safe JVM: the ceiling is authorization/ACL bypass + denial of service + cross-session integrity, **not RCE** (I did not find one and do not claim one). Audited at commit `da7f719a6bab9829d520b5838e13ea7b1f9be3ef`, module `broker/`.\n\n## What a connecting client can do\n\n1. (Critical) Bypass `pattern`-based ACLs across tenants. In `AuthorizationsCollector.canDoOperation` (AuthorizationsCollector.java:116-131, esp. line 123) the clientId/username is substituted raw into a pattern ACL rule and then wildcard-matched, and the clientId is never validated for MQTT wildcard characters +/# at CONNECT (MQTTConnection.processConnect):\n\nTopic substitutedTopic = new Topic(auth.topic.toString().replace(\"%c\", client).replace(\"%u\", username));\nif (topic.match(substitutedTopic)) return true;\n\nA client that connects with clientId + turns sensor/%c/# into the filter sensor/+/#, gaining cross-tenant read AND write. (Precondition: pattern ACL rules configured \u2014 a common multi-tenant setup.)\n\n2. (High) Crash the whole broker. SessionEventLoop (SessionEventLoop.java:40-54) catches only InterruptedException and is never restarted (SessionEventLoopGroup), so any uncaught exception on it wedges every co-located client. Trivially reachable inputs: malformed $share/grp SUBSCRIBE (SharedSubscriptionUtils.extractShareName -\u003e StringIndexOutOfBoundsException), deeply nested topic (CTrie recursion -\u003e StackOverflowError), and ACL NPE below. Unbounded subscriptions / retained / in-flight / topic-alias / interceptor state (BrokerInterceptor uses an unbounded queue) also allow OOM; durable stores allow disk exhaustion.\n\n3. (High) NPE in ACL sink on clientId # (invalid filter sensor/#/# -\u003e null tokens -\u003e Topic.match NPE at Topic.java:173).\n\n4. (High) Will-message authorization bypass. Last-Will topic is published (PostOffice.publishWill) without canWrite/reserved-topic checks used for normal PUBLISH.\n\n5. (Medium) Cross-session durable corruption. H2PersistentQueue opens queue_\"+clientId and queue_\"+clientId+\"_meta; client id sensor_meta collides with victim sensor metadata map -\u003e corrupts head/tail.\n\n6. (Medium) Fail-open if authenticator/authorizator class fails to load -\u003e PermitAll/AcceptAll (Server.java:483-531).\n\n## Proof of concept\n\nSource-only, no network; PoCs run on JDK 17:\n- PoCPatternAcl \u2014 clientId + gains cross-tenant read/write; clientId # triggers NPE\n- PoCSharedSubCrash \u2014 extractShareName(\"$share/grp\") throws StringIndexOutOfBoundsException\n- PoCMapCollision \u2014 H2 MVStore collision overwrites victim metadata pointer\n\n## Impact\n\nCross-tenant eavesdropping and injection, whole-broker DoS, unauthorized Will publishes, and cross-session durable corruption.\n\n## Remediation\n\n1. Reject clientId/username containing +/# (and / if structural) at CONNECT; expand %c/%u as literal tokens.\n2. Harden SessionEventLoop (catch Throwable + restart supervision) and validate $share filters.\n3. Apply authorization to Will publishes like normal PUBLISH.\n4. Add resource caps (connections, queues, retained, aliases, interceptor queue) + bounded session expiry.\n5. Separate H2 namespaces and fail closed on auth-class load failure.",
  "id": "GHSA-5f42-97gr-vfhq",
  "modified": "2026-09-23T16:11:18Z",
  "published": "2026-09-23T16:11:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/security/advisories/GHSA-5f42-97gr-vfhq"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/pull/957"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/pull/958"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/pull/959"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/commit/14a2f4fd280c8f6a791600c306cbccecb7c67007"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/commit/26498631e92d50440b4e3ed42fa546253cc4090c"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/commit/72d6c8257191d2e4b2e3aa11ab25fd09f88c6cb7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/commit/86feb7c31e6fac849c465d8079d08c0e7ef01cdf"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/commit/affdc71fdba92dc020421678970ae70518fb6da2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/commit/b4a98bb3f3425ece476ed073aa080c627c1239af"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/commit/c65b3e90fa03e562e2c2fa69c3ee916c2cbfbd2b"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/commit/ca17e0be19e86d5e291f4532dfdc94616c8e0049"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/commit/d77753542e262b7aa573dee3c2b05e44439bbd96"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/commit/f5a323fe782d1505c0097498cb22eb6ec6c96973"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/moquette-io/moquette"
    },
    {
      "type": "WEB",
      "url": "https://github.com/moquette-io/moquette/releases/tag/v0.18.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Moquette: Pattern-ACL wildcard injection (cross-tenant authorization bypass) plus a remote-unauthenticated DoS cluster, a Will-message authorization bypass, and a cross-session durable-corruption bug"
}

CVE-2026-85724 (GCVE-0-2026-85724)

Vulnerability from cvelistv5 – Published: 2026-09-23 16:29 – Updated: 2026-09-23 16:29

Title

Moquette pattern ACL wildcard injection allows cross-tenant authorization bypass

Summary

Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, when pattern-based ACL rules are configured, AuthorizationsCollector.canDoOperation substitutes client ID and username values directly into rules containing %c or %u and then treats the result as an MQTT topic filter. A client that uses + or # in either identity can broaden the substituted filter and gain cross-tenant read and write access. A # identity can also produce an invalid filter that triggers a NullPointerException in Topic.match and disrupts session processing. This issue is fixed in version 0.18.1.

Severity

9.6 (Critical)


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

CWE

CWE-863 - Incorrect Authorization
CWE-155 - Improper Neutralization of Wildcards or Matching Symbols

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/moquette-io/moquette/security/…	x_refsource_CONFIRM
https://github.com/moquette-io/moquette/commit/b4…	x_refsource_MISC
https://github.com/moquette-io/moquette/releases/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
moquette-io	moquette	Affected: < 0.18.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "moquette",
          "vendor": "moquette-io",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.18.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, when pattern-based ACL rules are configured, AuthorizationsCollector.canDoOperation substitutes client ID and username values directly into rules containing %c or %u and then treats the result as an MQTT topic filter. A client that uses + or # in either identity can broaden the substituted filter and gain cross-tenant read and write access. A # identity can also produce an invalid filter that triggers a NullPointerException in Topic.match and disrupts session processing. This issue is fixed in version 0.18.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 9.6,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-863",
              "description": "CWE-863: Incorrect Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-155",
              "description": "CWE-155: Improper Neutralization of Wildcards or Matching Symbols",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-23T16:29:36.296Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/moquette-io/moquette/security/advisories/GHSA-5f42-97gr-vfhq",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/moquette-io/moquette/security/advisories/GHSA-5f42-97gr-vfhq"
        },
        {
          "name": "https://github.com/moquette-io/moquette/commit/b4a98bb3f3425ece476ed073aa080c627c1239af",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/moquette-io/moquette/commit/b4a98bb3f3425ece476ed073aa080c627c1239af"
        },
        {
          "name": "https://github.com/moquette-io/moquette/releases/tag/v0.18.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/moquette-io/moquette/releases/tag/v0.18.1"
        }
      ],
      "source": {
        "advisory": "GHSA-5f42-97gr-vfhq",
        "discovery": "UNKNOWN"
      },
      "title": "Moquette pattern ACL wildcard injection allows cross-tenant authorization bypass"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-85724",
    "datePublished": "2026-09-23T16:29:36.296Z",
    "dateReserved": "2026-09-04T14:45:10.648Z",
    "dateUpdated": "2026-09-23T16:29:36.296Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.
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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.

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.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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