GHSA-g3pg-frfm-pr2m CVE-2026-61709 GO-2026-6488
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
Medium
Go
- Severity
- 5.3 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.35%
- Chance of exploitation in the next 30 days. Higher than 28.80% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Fix
1.18.1- Upgrade github.com/openfga/openfga to this version or later
Description
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.
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/openfga/openfga | < 1.18.1 |
1.18.1 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
github.com/openfga/openfga Go → 1.18.1
- go
go get github.com/openfga/openfga@v1.18.1 && go mod tidy
Severity breakdown
CVSS 3.1 5.3
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Weakness
CWE-281: Improper Preservation of Permissions
The product does not preserve permissions or incorrectly preserves permissions when copying, restoring, or sharing objects, which can cause them to have less restrictive permissions than intended.
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 to prevent it
- Architecture and Design: Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
- Architecture and Design: Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor [REF-7].
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
- Architecture and Design: For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page. One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.
- System Configuration, Installation: Use the access control capabilities of your operating system and server environment and define your access control lists accordingly. Use a "default deny" policy when defining these ACLs.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-hcxc-wf8j-23hv OpenFGA: OIDC audience validation skipped when --authn-oidc-audience is unset | High | Also affects github.com/openfga/openfga |
| GHSA-cf98-j28v-49v6 OpenFGA Improper Policy Enforcement | Medium | Also affects github.com/openfga/openfga |
| GHSA-8396-jffm-qx4w OpenFGA has cache-key delimiter injection in shared-iterator and v2 iterator that caches enables intra-store authorization-decision poisoning | Medium | Also affects github.com/openfga/openfga |
| GHSA-57j5-qwp2-vqp6 OpenFGA has Improper Policy Enforcement | Medium | Also affects github.com/openfga/openfga |
| GHSA-68m9-983m-f3v5 OpenFGA: Unauthenticated playground endpoint discloses preshared API key in HTML response | Medium | Also affects github.com/openfga/openfga |
| GHSA-jwvj-g8pc-cx45 OpenFGA's BatchCheck within-request deduplication produces incorrect authorization decisions via list-value cache-key collision | High | Also affects github.com/openfga/openfga |
| GHSA-h6c8-cww8-35hf OpenFGA has an Authorization Bypass through cached keys | Critical | Also affects github.com/openfga/openfga |
| GHSA-jq9f-gm9w-rwm9 OpenFGA Improper Policy Enforcement | High | Also affects github.com/openfga/openfga |
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