{"id":"CVE-2026-23996","aliases":["GHSA-95c6-p277-p87g","PYSEC-2026-1358"],"title":"FastAPI Api Key has a timing side-channel in verify_key that allows statistical key validity detection","summary":"FastAPI Api Key has a timing side-channel in verify_key that allows statistical key validity detection","severity":"low","cvss":3.7,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","vendor":"fastapi-api-key","product":"fastapi-api-key","ecosystem":"pip","affected":["fastapi-api-key < 1.1.0"],"patched":["fastapi-api-key 1.1.0"],"published":"2026-01-21","updated":"2026-07-07","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-95c6-p277-p87g","references":[{"url":"https://github.com/Athroniaeth/fastapi-api-key/security/advisories/GHSA-95c6-p277-p87g"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23996"},{"url":"https://github.com/Athroniaeth/fastapi-api-key/commit/310b2c5c77305f38c63c0b917539a0344071dfd8"},{"url":"https://github.com/Athroniaeth/fastapi-api-key"},{"url":"https://github.com/Athroniaeth/fastapi-api-key/releases/tag/1.1.0"}],"tags":["osv","pip"],"epss":0.00298,"epssPercentile":0.22662,"ingestedAt":"2026-07-08T18:25:47.753Z","slug":"CVE-2026-23996","body":"## Overview\n\n### Impact\nTiming 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.\n\nAffected: all users relying on verify_key() for API key authentication prior to the fix.\n\n### Patches\nYes. Users should upgrade to version 1.1.0 (or the version containing this fix). The patch applies a uniform random delay (min_delay to max_delay) to all responses regardless of outcome, eliminating the timing correlation.\n\n### Workarounds\n- Add an application-level fixed delay or random jitter to all authentication responses (success and failure) before the fix is applied.\n- Use rate limiting to reduce the feasibility of statistical timing attacks.\n\n### References\n- CWE-208: Observable Timing Discrepancy\n- Commit: 87b27640f77c5ef86c46311b6b5a7e2887e35b77\n- OWASP: https://owasp.org/www-community/attacks/Timing_attack\n\n## Affected packages\n\n- `fastapi-api-key < 1.1.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `fastapi-api-key 1.1.0`","depth":"sunlit","depthScore":20,"depthScoreParts":{"impact":20.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}