Cyber Resilience

CVE-2024-40627

Medium

Published: 15 July 2024

Published
15 July 2024
Modified
15 April 2026
KEV Added
Patch
CVSS Score v3.1 5.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
EPSS Score 0.0016 36.4th percentile
Risk Priority 12 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2024-40627 is a medium-severity Observable Response Discrepancy (CWE-204) vulnerability. Its CVSS base score is 5.8 (Medium).

Operationally, ranked at the 36.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

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…

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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.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-204

Fake or randomized responses remove distinguishable success/failure signals attackers rely on.

addresses: CWE-204

Eliminates distinguishable response discrepancies in error conditions that could be exploited for reconnaissance.

References