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

{
    "lastseen": "",
    "description": "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.",
    "published": "2026-01-21T22:29:24.107Z",
    "modified": "2026-01-22T16:49:16.733Z",
    "type": "cve",
    "title": "FastAPI Api Key has a timing side-channel in verify_key that allows statistical key validity detection",
    "source": "GitHub_M",
    "references": "https://github.com/Athroniaeth/fastapi-api-key/security/advisories/GHSA-95c6-p277-p87g\nhttps://github.com/Athroniaeth/fastapi-api-key/commit/310b2c5c77305f38c63c0b917539a0344071dfd8\nhttps://github.com/Athroniaeth/fastapi-api-key/releases/tag/1.1.0",
    "id": "CVE-2026-23996",
    "bulletinFamily": "",
    "cwe": [
        "CWE-208"
    ],
    "cvelist": null,
    "sourceData": "Athroniaeth fastapi-api-key < 1.1.0",
    "sourceHref": "",
    "cvss": {
        "score": 3.7,
        "severity": "LOW",
        "vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
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        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
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            "baseScore": 0,
            "baseSeverity": "",
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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "fastapi-api-key",
    "version": "< 1.1.0",
    "vendor": "Athroniaeth",
    "ai_description": "",
    "ai_severity": "",
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    "ai_score": 0
}