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

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No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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.

Source published

16 Sep 2026 14:05:35 UTC

Source modified

18 Sep 2026 17:52:34 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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

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.

Source published

Sep 16, 2026, 2:05:35 PM (timezone not stated)

Source modified

Sep 18, 2026, 5:52:34 PM (timezone not stated)

Observed here

11 Nov 2026 15:03:03 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

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

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.

Source published

16 Sep 2026 15:17:39 UTC

Source modified

24 Sep 2026 21:25:27 UTC

Observed here

25 Oct 2026 14:19:22 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

### 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.

Source published

16 Sep 2026 22:15:09 UTC

Source modified

28 Sep 2026 17:11:12 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Publisher rating · MODERATE

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 in github.com/openfga/openfga

Source published

28 Sep 2026 16:43:40 UTC

Source modified

28 Sep 2026 17:00:17 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.