CVE-2026-121506High· 7.4▾ TwilightAn 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, …
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 40.7 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Exploit-prediction probability, daily snapshots since Nov 5.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
0.4%
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.
NTPsec >= 1.1.4 < 1.2.5Upgrade to version 1.2.5 or above.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-121505Low· 3.7Out-of-bounds Read in NTPsec
CVE-2026-102485Medium· 5.2Out-of-bounds Read in ntpsec
CVE-2026-102483High· 7.5Reachable Assertion in ntpsec
CVE-2026-102484Medium· 6.4Heap-based Buffer Overflow in ntpsec
CVE-2026-102486High· 7.5Out-of-bounds Read in ntpsec
CVE-2021-22555High· 8.3A heap out-of-bounds write affecting Linux since v2.6.19-rc1 was discovered in net/netfilter/x_tables.c