CVE-2024-40627
CVE-2024-40627 is a medium-severity vulnerability with a CVSS 3.x base score of 5.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-204.
Key facts
- Severity: Medium (CVSS 3.x base score 5.8)
- EPSS exploit prediction: 1% (43rd percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2024-2263
- Weakness: CWE-204
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2024-40627?
- 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.
- How severe is CVE-2024-40627?
- CVE-2024-40627 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
- Is CVE-2024-40627 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2024-40627?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2024-40627 have an EU (EUVD) identifier?
- Yes. CVE-2024-40627 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-2263.
- When was CVE-2024-40627 published?
- CVE-2024-40627 was published on 2024-07-15 and last updated on 2026-06-17.
References
- https://github.com/busykoala/fastapi-opa/blob/6dd6f8c87e908fe080784a74707f016f1422b58a/fastapi_opa/opa/opa_middleware.py#L79-L80
- https://github.com/busykoala/fastapi-opa/commit/9588109ff651f7ffc92687129c4956126443fb8c
- https://github.com/busykoala/fastapi-opa/security/advisories/GHSA-5f5c-8rvc-j8wf
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