{"id":"CVE-2021-42143","aliases":["EUVD-2021-29126","GHSA-23p4-xxgc-xqvf"],"status":"published","title":"An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop...","description":"An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop bug exists during the handling of a ClientHello handshake message. This bug allows remote attackers to cause a denial of service by sending a malformed ClientHello handshake message with an odd length of cipher suites, which triggers an infinite loop (consuming all resources) and a buffer over-read that can disclose sensitive information.","severity":{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","level":"critical","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-12","score":0.00812,"percentile":0.57461,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-835"],"published":"2024-01-24T00:00:00Z","modified":"2026-06-17T04:09:25Z","products":[{"vendor":"contiki-ng","product":"tinydtls"}],"references":[{"url":"https://seclists.org/fulldisclosure/2024/Jan/16","tags":["x_transferred","Mailing List","Third Party Advisory"]},{"url":"http://seclists.org/fulldisclosure/2024/Jan/16"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-42143"},{"url":"https://github.com/advisories/GHSA-23p4-xxgc-xqvf"}],"sources":{"cve":[{"id":"CVE-2021-42143","description":"An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop bug exists during the handling of a ClientHello handshake message. This bug allows remote attackers to cause a denial of service by sending a malformed ClientHello handshake message with an odd length of cipher suites, which triggers an infinite loop (consuming all resources) and a buffer over-read that can disclose sensitive information.","status":"published","published":"2024-01-24T00:00:00Z","modified":"2025-06-20T19:16:00.614Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","level":"critical","assessor":"adp"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T14:32:58.739039Z"}],"euvd":[{"id":"EUVD-2021-29126","description":"An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop bug exists during the handling of a ClientHello handshake message. This bug allows remote attackers to cause a denial of service by sending a malformed ClientHello handshake message with an odd length of cipher suites, which triggers an infinite loop (consuming all resources) and a buffer over-read that can disclose sensitive information.","status":"published","published":"2024-01-24T00:00:00Z","modified":"2025-06-20T19:16:00Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","level":"critical"}],"updated_at":"2026-11-02T20:32:18.601981Z"}],"ghsa":[{"id":"GHSA-23p4-xxgc-xqvf","title":"An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop...","description":"An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop bug exists during the handling of a ClientHello handshake message. This bug allows remote attackers to cause a denial of service by sending a malformed ClientHello handshake message with an odd length of cipher suites, which triggers an infinite loop (consuming all resources) and a buffer over-read that can disclose sensitive information.","status":"published","published":"2024-01-24T18:31:01Z","modified":"2025-06-20T21:32:59Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","level":"critical"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T15:02:47.356918Z"}],"nvd":[{"id":"CVE-2021-42143","description":"An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. An infinite loop bug exists during the handling of a ClientHello handshake message. This bug allows remote attackers to cause a denial of service by sending a malformed ClientHello handshake message with an odd length of cipher suites, which triggers an infinite loop (consuming all resources) and a buffer over-read that can disclose sensitive information.","status":"published","published":"2024-01-24T18:15:08.08Z","modified":"2026-06-17T04:09:25.39Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","level":"critical","assessor":"primary"},{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","level":"critical","assessor":"secondary"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T14:07:08.163458Z"}]}}