CVE-2026-23996

FastAPI Api Key provides a backend-agnostic library that provides an API key system. Version 1.1.0 has a timing side-channel vulnerability in verify_key(). The method applied a random delay only on verification failures, allowing an attacker to statistically distinguish valid from invalid API keys by measuring response latencies. With enough repeated requests, an adversary could infer whether a key_id corresponds to a valid key, potentially accelerating brute-force or enumeration attacks. All users relying on verify_key() for API key authentication prior to the fix are affected. Users should upgrade to version 1.1.0 to receive a patch. The patch applies a uniform random delay (min_delay to max_delay) to all responses regardless of outcome, eliminating the timing correlation. Some workarounds are available. Add an application-level fixed delay or random jitter to all authentication responses (success and failure) before the fix is applied and/or use rate limiting to reduce the feasibility of statistical timing attacks.

CVSS v3 3.7 LOW

3.7^/10

CVSS v3 : LOW

Vector :

Exploitability : 2.2 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/Athroniaeth/fastapi-api-key/commit/310b2c5c77305f38c63c0b917539a0344071dfd8	Patch
https://github.com/Athroniaeth/fastapi-api-key/releases/tag/1.1.0	Product Release Notes
https://github.com/Athroniaeth/fastapi-api-key/security/advisories/GHSA-95c6-p277-p87g	Mitigation Patch Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:athroniaeth:fastapi_api_key:*:*:*:*:*:python:*:*

History

No history.

Information

Published : 2026-01-21 23:15

Updated : 2026-02-27 14:52

NVD link : CVE-2026-23996

Mitre link : CVE-2026-23996

CVE.ORG link : CVE-2026-23996

JSON object : View

Products Affected

athroniaeth

fastapi_api_key

CWE

CWE-208

Observable Timing Discrepancy

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