Vulnerability-Lookup

GHSA-G3PG-FRFM-PR2M

Vulnerability from github – Published: 2026-09-16 22:15 – Updated: 2026-09-16 22:15

Summary

OpenFGA: ListUsers returns a deliberately-excluded user when a `but not` exclusion under a type-bound wildcard is intersected (`and`) with another relation that also grants that user

Details

Description

In OpenFGA, the ListUsers API could incorrectly return a user who should have been excluded.

Preconditions

This applies if all of the following are present:

The authorization model contains a relation defined as an intersection (and) where at least one operand is an exclusion of the form base but not excluded: e.g. rel1: (public_user but not blocked) and rel2
The base side of that exclusion is granted through a type-bound public wildcard (e.g. user:*).
A user excluded by the but not clause is also granted, via a concrete tuple, through another operand of the intersection.
Your application uses ListUsers to enumerate or enforce access

Fix

Upgrade to OpenFGA v1.18.1 or greater.

Acknowledgements

OpenFGA would like to thank @5ud0er for the detailed report.

Severity

5.3 (Medium)


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

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JSON

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.18.0"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/openfga/openfga"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.18.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-61709"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-281",
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-16T22:15:09Z",
    "nvd_published_at": "2026-09-16T15:17:39Z",
    "severity": "MODERATE"
  },
  "details": "### Description\n\nIn OpenFGA, the ListUsers API could incorrectly return a user who should have been excluded.\n\n\n### Preconditions\n\nThis applies if all of the following are present:\n\n- The authorization model contains a relation defined as an intersection (and) where at least one operand is an exclusion of the form base but not excluded: e.g. `rel1: (public_user but not blocked) and rel2`\n- The base side of that exclusion is granted through a type-bound public wildcard (e.g. user:*).\n- A user excluded by the but not clause is also granted, via a concrete tuple, through another operand of the intersection.\n- Your application uses ListUsers to enumerate or enforce access\n\n### Fix\n\nUpgrade to OpenFGA v1.18.1 or greater.\n\n### Acknowledgements\n\nOpenFGA would like to thank @5ud0er for the detailed report.",
  "id": "GHSA-g3pg-frfm-pr2m",
  "modified": "2026-09-16T22:15:09Z",
  "published": "2026-09-16T22:15:09Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/openfga/openfga/security/advisories/GHSA-g3pg-frfm-pr2m"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-61709"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openfga/openfga/commit/171806c93b86bca29e0212ceb8b6ee9c48eb9ac3"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/openfga/openfga"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openfga/openfga/releases/tag/v1.18.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "OpenFGA: ListUsers returns a deliberately-excluded user when a `but not` exclusion under a type-bound wildcard is intersected (`and`) with another relation that also grants that user"
}

CVE-2026-61709 (GCVE-0-2026-61709)

Vulnerability from cvelistv5 – Published: 2026-09-16 14:05 – Updated: 2026-09-16 14:05

Title

OpenFGA: ListUsers returns a deliberately-excluded user (authorization-decision over-inclusion) when a `but not` exclusion under a type-bound wildcard is intersected (`and`) with another relation that also grants that user

Summary

OpenFGA is an authorization and permission engine built for developers. Prior to 1.18.1, the ListUsers API could return a user that should have been excluded when an authorization relation used an intersection containing a base but not excluded operand, the base was granted through a type-bound public wildcard, and the excluded user also had a concrete tuple through another intersection operand. In pkg/server/commands/listusers/list_users_rpc.go, expandIntersection counted the concrete tuple and wildcard without first rejecting entries in excludedUsersMap. Applications that used ListUsers to enumerate or enforce access could therefore treat an excluded user as authorized. This issue is fixed in version 1.18.1.

Severity

5.3 (Medium)


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

CWE

CWE-281 - Improper Preservation of Permissions
CWE-863 - Incorrect Authorization

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/openfga/openfga/security/advis…	x_refsource_CONFIRM
https://github.com/openfga/openfga/commit/171806c…	x_refsource_MISC
https://github.com/openfga/openfga/releases/tag/v1.18.1	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
openfga	openfga	Affected: < 1.18.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "openfga",
          "vendor": "openfga",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.18.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "OpenFGA is an authorization and permission engine built for developers. Prior to 1.18.1, the ListUsers API could return a user that should have been excluded when an authorization relation used an intersection containing a base but not excluded operand, the base was granted through a type-bound public wildcard, and the excluded user also had a concrete tuple through another intersection operand. In pkg/server/commands/listusers/list_users_rpc.go, expandIntersection counted the concrete tuple and wildcard without first rejecting entries in excludedUsersMap. Applications that used ListUsers to enumerate or enforce access could therefore treat an excluded user as authorized. This issue is fixed in version 1.18.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-281",
              "description": "CWE-281: Improper Preservation of Permissions",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-863",
              "description": "CWE-863: Incorrect Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-16T14:05:35.455Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/openfga/openfga/security/advisories/GHSA-g3pg-frfm-pr2m",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/openfga/openfga/security/advisories/GHSA-g3pg-frfm-pr2m"
        },
        {
          "name": "https://github.com/openfga/openfga/commit/171806c93b86bca29e0212ceb8b6ee9c48eb9ac3",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/openfga/openfga/commit/171806c93b86bca29e0212ceb8b6ee9c48eb9ac3"
        },
        {
          "name": "https://github.com/openfga/openfga/releases/tag/v1.18.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/openfga/openfga/releases/tag/v1.18.1"
        }
      ],
      "source": {
        "advisory": "GHSA-g3pg-frfm-pr2m",
        "discovery": "UNKNOWN"
      },
      "title": "OpenFGA: ListUsers returns a deliberately-excluded user (authorization-decision over-inclusion) when a `but not` exclusion under a type-bound wildcard is intersected (`and`) with another relation that also grants that user"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-61709",
    "datePublished": "2026-09-16T14:05:35.455Z",
    "dateReserved": "2026-07-10T18:51:13.919Z",
    "dateUpdated": "2026-09-16T14:05:35.455Z",
    "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.
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.
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.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.