CVE-2026-23996— FastAPI Api Key has a timing side-channel in verify_key that allows statistical key validity detection

FastAPI Api Key has a timing side-channel in verify_key that allows statistical key validity detection

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:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

通过时间差异性导致的信息暴露

FastAPI Api Key 安全漏洞

FastAPI Api Key是Athroniaeth个人开发者的一个安全密钥库。 FastAPI Api Key 1.1.0版本存在安全漏洞，该漏洞源于verify_key方法存在时序侧信道，可能导致攻击者通过测量响应延迟来推断API密钥的有效性。

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