{"id":"CVE-2026-121506","aliases":["DEBIAN-CVE-2026-121506","EUVD-2026-115827","GHSA-28fm-m2x6-h5pf","UBUNTU-CVE-2026-121506"],"status":"published","title":"Out-of-bounds Write in NTPsec","description":"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, 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.","severity":{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00449,"percentile":0.39502,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-787"],"published":"2026-11-03T14:17:24Z","modified":"2026-11-06T16:00:06Z","fixes":[{"ecosystem":"Debian:14","package":"ntpsec","fixed_in":["1.2.5+dfsg-1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"ntpsec","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.2+dfsg1-1","1.2.2+dfsg1-1+deb12u1","1.2.2+dfsg1-2","1.2.2+dfsg1-3","1.2.2+dfsg1-4","1.2.3+dfsg1-1","1.2.3+dfsg1-2","1.2.3+dfsg1-3","1.2.3+dfsg1-4","1.2.3+dfsg1-5","1.2.3+dfsg1-6","1.2.3+dfsg1-7","1.2.3+dfsg1-8","1.2.4+dfsg-1","1.2.5+dfsg-1"]},{"source":"osv","ecosystem":"Debian:13","package":"ntpsec","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.3+dfsg1-8","1.2.4+dfsg-1","1.2.5+dfsg-1"]},{"source":"osv","ecosystem":"Debian:14","package":"ntpsec","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.5+dfsg-1"}]}],"versions":["1.2.3+dfsg1-8","1.2.4+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"ntpsec","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.0+dfsg1-1","1.0.0+dfsg1-3","1.1.0+dfsg1-1","1.1.0+dfsg1-1ubuntu0.1","1.1.0+dfsg1-1ubuntu0.2"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"ntpsec","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.3+dfsg1-2","1.1.7+dfsg1-1","1.1.7+dfsg1-2","1.1.8+dfsg1-1","1.1.8+dfsg1-3","1.1.8+dfsg1-4","1.1.8+dfsg1-4build1"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"ntpsec","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.0+dfsg1-4","1.2.1+dfsg1-2","1.2.1+dfsg1-3","1.2.1+dfsg1-3ubuntu1","1.2.1+dfsg1-4"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"ntpsec","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.2+dfsg1-2","1.2.2+dfsg1-3","1.2.2+dfsg1-4","1.2.2+dfsg1-4build1","1.2.2+dfsg1-4build2"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"ntpsec","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.3+dfsg1-8ubuntu2","1.2.3+dfsg1-8ubuntu3"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"ntpsec","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.3+dfsg1-8ubuntu1","1.2.3+dfsg1-8ubuntu2"]}],"products":[{"vendor":"ntpsec","product":"ntpsec"}],"references":[{"url":"https://gitlab.com/NTPsec/ntpsec/-/commit/0a36941e499d533dfbc3fb6b1fcd8c367679d719","tags":["fix","report"]},{"url":"https://gitlab.com/NTPsec/ntpsec/-/work_items/902","tags":["web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121506","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-28fm-m2x6-h5pf"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/121xxx/CVE-2026-121506.json","tags":["advisory"]},{"url":"https://gitlab.com/NTPsec/ntpsec","tags":["package"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-121506","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-121506","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-121506","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-121506","title":"Out-of-bounds Write in NTPsec","description":"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, 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.","status":"published","published":"2026-11-03T14:17:24.651Z","modified":"2026-11-03T15:29:28.236Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-787"],"updated_at":"2026-11-03T16:58:09.635057Z"}],"euvd":[{"id":"EUVD-2026-115827","description":"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, 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.","status":"published","published":"2026-11-03T14:17:24Z","modified":"2026-11-03T15:29:28Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"high"}],"updated_at":"2026-11-03T18:19:05.216794Z"}],"ghsa":[{"id":"GHSA-28fm-m2x6-h5pf","title":"An out-of-bounds read and write in NTS client extension field parsing (extens_client_recv) in...","description":"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, 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.","status":"published","published":"2026-11-03T15:32:20Z","modified":"2026-11-03T15:32:24Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"high"}],"cwes":["CWE-787"],"updated_at":"2026-11-03T15:57:23.404697Z"}],"nvd":[{"id":"CVE-2026-121506","description":"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, 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.","status":"published","published":"2026-11-03T15:17:37.717Z","modified":"2026-11-03T16:17:24.84Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-787"],"updated_at":"2026-11-03T18:16:47.713454Z"}],"osv":[{"id":"CVE-2026-121506","title":"Out-of-bounds Write in NTPsec","description":"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, 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.","status":"published","published":"2026-11-03T14:17:24.651Z","modified":"2026-11-05T03:31:09.808852856Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"high"}],"cwes":["CWE-787"],"updated_at":"2026-11-05T07:12:46.161235Z"},{"id":"DEBIAN-CVE-2026-121506","description":"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, 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.","status":"published","published":"2026-11-03T15:17:37.717Z","modified":"2026-11-06T16:00:06.735349153Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"high"}],"updated_at":"2026-11-06T16:28:46.165024Z"},{"id":"UBUNTU-CVE-2026-121506","description":"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, 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.","status":"published","published":"2026-11-03T15:17:00Z","modified":"2026-11-05T11:46:31.486340939Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"high"}],"updated_at":"2026-11-05T13:30:15.321876Z"}]}}