CVE-2023-43645 is a medium-severity (CVSS 5.9) CWE-835 vulnerability in github.com/openfga/openfga. A fix is available for github.com/openfga/openfga — see the affected versions and patch details below.
Denial of service from circular relationship definitions in OpenFGA
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-43645.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/openfga/openfgaReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Overview
OpenFGA is vulnerable to a DoS attack when certain Check calls are executed against authorization models that contain circular relationship definitions. When the call is made, it's possible for the server to exhaust resources and die.
Am I Affected?
Yes, if your store contains an authorization model that allows circular relationships. For example, with this model:
model
schema 1.1
type user
type group
relations
define memberA: [user] or memberB or memberC or memberD or memberE
define memberB: [user] or memberA or memberC or memberD or memberE
define memberC: [user] or memberA or memberB or memberD or memberE
define memberD: [user] or memberA or memberB or memberC or memberE
define memberE: [user] or memberA or memberB or memberC or memberD
This Check: (user:anne, memberA, group:X) can exhaust memory in the server.
Fix
Upgrade to v1.3.2 and update any offending models.
[BREAKING] If your model contained cycles or a relation definition that has the relation itself in its evaluation path, then Checks and queries that require evaluation will no longer be evaluated on v1.3.2+ and will return errors instead. You will need to update your models to remove the cycles.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/openfga/openfga | all versions | 1.3.2go get github.com/openfga/openfga@v1.3.2 |
Affected Products
openfgaopenfgaDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/openfga/openfga, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/openfga/openfga to 1.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-43645 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2023-43645 in your dependencies?
Find it across Go, including transitive dependencies.