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
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
Acknowledgements
OpenFGA would like to thank @5ud0er for the detailed report.
Impact
The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.
CVE-2026-61709 has a CVSS score of 5.3 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.18.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Upgrade to OpenFGA v1.18.1 or greater.
Frequently Asked Questions
- What is CVE-2026-61709? CVE-2026-61709 is a medium-severity incorrect authorization vulnerability in github.com/openfga/openfga (go), affecting versions <= 1.18.0. It is fixed in 1.18.1. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
- How severe is CVE-2026-61709? CVE-2026-61709 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/openfga/openfga are affected by CVE-2026-61709? github.com/openfga/openfga (go) versions <= 1.18.0 is affected.
- Is there a fix for CVE-2026-61709? Yes. CVE-2026-61709 is fixed in 1.18.1. Upgrade to this version or later.
- Is CVE-2026-61709 exploitable, and should I be worried? Whether CVE-2026-61709 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-61709 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-61709? Upgrade
github.com/openfga/openfgato 1.18.1 or later.