CVE-2026-61709: OpenFGA ListUsers Returns A Deliberately-excluded User Vulnerability

MODERATE
Advisory Identifier: GHSA-g3pg-frfm-pr2m
Share
CVSS 5.3
CWE-863 CWE-281
Published
Advisory Summary

CVE-2026-61709 is a MODERATE (CVSS 5.3) listusers returns a deliberately-excluded user vulnerability (CWE-863: Incorrect Authorization) affecting OpenFGA libraries in the Go ecosystem. The issue involves 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. Remediation is available by upgrading affected packages to version 1.18.1.

CVE-2026-61709 at a Glance

CVE Identifier CVE-2026-61709
GHSA Identifier GHSA-g3pg-frfm-pr2m
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-863: Incorrect Authorization
Affected Product OpenFGA
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 5.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-61709

To remediate this vulnerability, upgrade all affected OpenFGA dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/openfga/openfga fixed: 1.18.1 
Upgrade github.com/openfga/openfga to 1.18.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/openfga/openfga

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-61709, inspect your project dependencies for OpenFGA:

inspect dependencies for github.com/openfga/openfga

Analyze the terminal output to locate any version of OpenFGA in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.18.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-863: Incorrect Authorization, where the product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. In OpenFGA, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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.

CVE-2026-61709 Affected OpenFGA Versions

1 component(s)
Fixed Versions:
1.18.1
Product / Package Ecosystem Affected Versions Fixed Version
github.com/openfga/openfga
golang/github.com/openfga/openfga
Go
< 1.18.1
1.18.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/openfga/openfga/security/advisories/GHSA-g3pg-frfm-pr2m
NVD — CVE-2026-61709 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-61709
Security Fix Commit FIX COMMIT
https://github.com/openfga/openfga/commit/171806c93b86bca29e0212ceb8b6ee9c48eb9ac3
OpenFGA Source Repository REPOSITORY
https://github.com/openfga/openfga
OpenFGA Release RELEASE
https://github.com/openfga/openfga/releases/tag/v1.18.1

Frequently Asked Questions

What is CVE-2026-61709?
CVE-2026-61709 is a security vulnerability in OpenFGA involving 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 under CWE-863: Incorrect Authorization.
Which OpenFGA versions are affected?
Affected versions include releases prior to 1.18.1 across affected packages: github.com/openfga/openfga.
What version fixes CVE-2026-61709?
Upgrading to 1.18.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/openfga/openfga affected?
Yes, github.com/openfga/openfga is affected in releases prior to 1.18.1. Upgrade your dependency to 1.18.1 or later.
What is the CVSS score of CVE-2026-61709?
CVE-2026-61709 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-61709?
CVE-2026-61709 is classified under CWE-863: Incorrect Authorization (The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.).
How can I check Go dependencies for CVE-2026-61709?
Run the dependency tree command: 'inspect dependencies for github.com/openfga/openfga'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-g3pg-frfm-pr2m",
  "modified" : "2026-09-16T22:15:09Z",
  "published" : "2026-09-16T22:15:09Z",
  "aliases" : [ "CVE-2026-61709" ],
  "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\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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/openfga/openfga"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.18.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.18.0"
    }
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-281", "CWE-863" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-16T22:15:09Z",
    "nvd_published_at" : "2026-09-16T15:17:39Z"
  }
}