Description
Fastapi OPA is an opensource fastapi middleware which includes auth flow. HTTP `OPTIONS` requests are always allowed by `OpaMiddleware`, even when they lack authentication, and are passed through directly to the application. `OpaMiddleware` allows all HTTP `OPTIONS` requests without evaluating it against any policy. If an application provides different responses to HTTP `OPTIONS` requests based on an entity existing (such as to indicate whether an entity is writable on a system level), an unauthenticated attacker could discover which entities exist within an application. This issue has been addressed in release version 2.0.1. All users are advised to upgrade. There are no known workarounds for this vulnerability.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| busykoala | fastapi-opa | < 2.0.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | fastapi | No fix yet | — |
| Ubuntu 26.04 LTS | fastapi | No fix yet | — |
| Ubuntu 25.10 | fastapi | No fix yet | — |
| Ubuntu 24.04 LTS | fastapi | No fix yet | — |
| Ubuntu 22.04 LTS | fastapi | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | fastapi-opa | < 2.0.1 | 2.0.1 | GHSA-5f5c-8rvc-j8wf |