OpenFGA is a powerful open-source authorization/permissions engine quickly gaining ground in cloud native applications. But like all fast-evolving platforms, it sometimes gets hit by serious vulnerabilities. This is the case with CVE-2024-56323, a recently disclosed flaw that may allow attackers to bypass authorization checks in certain situations. This article breaks down the issue in plain English, outlines how it can be exploited, and offers code snippets and references for remediation.

What Is CVE-2024-56323?

In simple terms, CVE-2024-56323 is a critical vulnerability in OpenFGA versions v1.3.8 through v1.8.2. Under specific conditions, the service can incorrectly authorize access, letting users see or interact with resources they shouldn’t.

You're vulnerable to this bug if all the following are true

- (1) You call the Check or ListObjects API using a model that uses conditions.
- (2) Your API calls use contextual tuples _with conditions_.

The Basics

OpenFGA lets you define _authorization models_n with conditions. You can also pass contextual tuples at query time, adding dynamic facts to authorization checks.

Caching is used to speed up access queries. But when contextual tuples (especially with conditions) are involved, OpenFGA did not always treat these context-sensitive queries as unique for cache purposes. This means a previous authorization result using a _different_ context might be incorrectly reused for a new request.

The Problem

If a user made an authorized request with some contextual tuple and condition (which is cached), and another user (with different context or tuple conditions) made a subsequent request, OpenFGA could reuse the earlier (less restrictive) result from cache.

Result: Authorization bypass.
A user may be told they have access to something they shouldn't, depending on what was cached earlier.

Exploit Scenario (Code Example)

Let's look at a simple scenario to see how this plays out.

1. Example Authorization Model with a Condition

{
  "type_definitions": [
    {
      "type": "document",
      "relations": {
        "viewer": {
          "union": {
            "child": [
              {
                "this": {}
              },
              {
                "computedUserset": {
                  "relation": "reader"
                }
              }
            ]
          }
        }
      },
      "conditions": {
        "after_deadline": {
          "expression": "request_time > document.deadline"
        }
      }
    }
  ]
}

Let’s say an API call is made

POST /check
{
  "user": "user:alice",
  "relation": "viewer",
  "object": "document:doc1",
  "contextual_tuples": [
    {
      "user": "user:alice",
      "relation": "viewer",
      "object": "document:doc1",
      "condition": {
        "name": "after_deadline",
        "context": { "request_time": "2024-07-01T12:00:00Z" }
      }
    }
  ]
}

What's Intended

Alice should be a viewer of doc1 only if her request is after the document's deadline.

The Vulnerable Condition

If this check is cached and then Bob tries a similar request but at a time before the deadline, OpenFGA might reply "allowed" — reusing the cached "allowed" outcome, instead of performing the new check!

3. Hitting the Vulnerability

Step 1: Authorized user queries with request_time > deadline, result is "allowed" and cached.

Step 2: Another user (or same user with different tuple/context) queries with request_time < deadline.
Cached result is used → system grants access when it shouldn't.

No Workarounds Available

The OpenFGA devs have made it clear in their advisory and CVE record:
> "There are NO known workarounds. You must upgrade."

`

or check your Docker/Helm version.

Upgrade to OpenFGA v1.8.3 or later:

- Release notes

helm repo update

helm upgradeopenfga/openfga --version .2.20

`bash

docker pull openfga/openfga:v1.8.3

Version is at least 1.8.3

- OPENFGA_CHECK_QUERY_CACHE_ENABLED is still default/desired (no need to disable after upgrade – the logic is fixed)
- Tests: Run integration tests involving conditions and contextual tuples. Ensure no cross-result leakage.


## References / More Info

- GitHub Security Advisory (GHSA-7j8f-pp7r-fggx)
- NVD CVE Record (CVE-2024-56323)
- OpenFGA Modeling Conditions
- OpenFGA Contextual Tuples
- OpenFGA Releases

Final Thoughts

This bug reminds us that cache logic + complex conditions + dynamic contexts = potential for subtle, dangerous authorization bypasses. If you use OpenFGA and rely on contextual tuples, please stop everything and upgrade — you do not want to be caught exposing confidential data or granting access in error!

Stay safe. Patch your systems. Share with your security teams.

If you want more technical background or help validating your fix, head over to the GitHub discussion or leave a comment below.

Timeline

Published on: 01/13/2025 22:15:14 UTC