CVE-2026-121506
Out-of-bounds Write in NTPsec
CVSS Score
7.4
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-787 |
| Vendor | ntpsec |
| Product | ntpsec |
| Published | Nov 3, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High
Affected Versions
NTPsec / NTPsec
1.1.4 < 1.2.5
References
Credits
Found by OSS-Fuzz (issue 393742176); Erica Windisch (Cyberdione Labs) analyzed its impact