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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-61709: 0.35% estimated exploitation activity in the next 30 days; percentile 28.83 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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: (publicuser 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.

Published by the source

16 Sep 2026, 22:15 UTC

Last modified by the source

28 Sep 2026, 17:00 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-g3pg-frfm-pr2m

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6488

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-g3pg-frfm-pr2m

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# Patch Next advisory brief: CVE-2026-61709

Advisory: 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
IDs: CVE-2026-61709, GHSA-g3pg-frfm-pr2m
Record: https://patchnext.com/advisories/cve-2026-61709 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/openfga/openfga 1.18.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/openfga/openfga: affected <= 1.18.0; fixed in 1.18.1

## Suggested inspection (read-only)
- Go github.com/openfga/openfga: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/openfga/openfga.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-g3pg-frfm-pr2m (OSV record GHSA-g3pg-frfm-pr2m lists affected ranges: Go github.com/openfga/openfga >=0 <1.18.1 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6488 (OSV record GO-2026-6488 lists affected ranges: Go github.com/openfga/openfga >=0 <1.18.1 (fixed))
- Verified: https://github.com/advisories/GHSA-g3pg-frfm-pr2m (GitHub-reviewed advisory GHSA-g3pg-frfm-pr2m lists affected ranges: Go github.com/openfga/openfga >=0 <=1.18.0)

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