{"cve":"CVE-2021-43203","nvd":{"published":"2021-11-09T15:15:10.110","modified":"2026-06-17T04:10:38.210","status":"Modified","description":"In JetBrains Ktor before 1.6.4, nonce verification during the OAuth2 authentication process is implemented improperly.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","score":7.5},"cwes":["CWE-287"],"references":["https://blog.jetbrains.com/blog/2021/11/08/jetbrains-security-bulletin-q3-2021/","https://blog.jetbrains.com/blog/2021/11/08/jetbrains-security-bulletin-q3-2021/"],"products":["jetbrains:ktor"],"source":"nvd","synced_at":"2026-10-19T21:24:39.218183596+00:00"},"epss":{"cve":"CVE-2021-43203","score":0.00864,"percentile":0.58639,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}