Medium severity · published Jul 31, 2026
CVE-2026-18321
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') in ntpsec
4.7
CVSS
0.1%
EPSS
No
On KEV
Description
Buffer overflow in NTPsec's Zyfer refclock allows local attacker to crash ntpd
CVSS vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Local
Complexity
High
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 1% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NT
ntpsec · NTPsec
before 1.2.5 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-18321
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-18321
gitlab.com
https://gitlab.com/NTPsec/ntpsec/-/work_items/890
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