{"id":"CVE-2026-121506","title":"Out-of-bounds Write in NTPsec","summary":"An out-of-bounds read and write in NTS client extension field parsing (extens_client_recv) in NTPsec before 1.2.5 allows a remote attacker who can send NTP server-mode replies to an NTS client to corrupt heap memory and crash ntpd, and, …","severity":"high","cvss":7.4,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","cvssSource":"cna","cwe":["CWE-787"],"vendor":"NTPsec","product":"NTPsec","affected":["NTPsec >= 1.1.4 < 1.2.5"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-03T15:15:17.727246Z"},"published":"2026-11-03","updated":"2026-11-03","sourceUpdated":"2026-11-03T15:29:28.236Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-121506","references":[{"url":"https://gitlab.com/NTPsec/ntpsec/-/commit/0a36941e499d533dfbc3fb6b1fcd8c367679d719"},{"url":"https://gitlab.com/NTPsec/ntpsec/-/work_items/902"}],"tags":["cve.org"],"epss":0.00449,"epssPercentile":0.39256,"ingestedAt":"2026-11-05T19:30:42.986Z","slug":"CVE-2026-121506","body":"## Overview\n\nAn out-of-bounds read and write in NTS client extension field parsing (extens_client_recv) in NTPsec before 1.2.5 allows a remote attacker who can send NTP server-mode replies to an NTS client to corrupt heap memory and crash ntpd, and, combined with the NTS-KE client out-of-bounds read fixed in 1.2.4, to bypass NTS authentication and set the client's time, via an NTS Authenticator and Encrypted Extension Fields field whose nonce length exceeds the field.\n\n## Affected\n\n- `NTPsec >= 1.1.4 < 1.2.5`\n\n## Remediation\n\nUpgrade to version 1.2.5 or above.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":40.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}