Vulnerability · Published Jul 31, 2026 · Assigned by GitLab
CVE-2026-18321Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') in ntpsec
Medium 4.7
In plain English
A medium-severity buffer overflow in ntpsec from NTPsec. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)4.7Medium
Exploit odds (30 days)0.1%top 98.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Buffer overflow in NTPsec's Zyfer refclock allows local attacker to crash ntpd
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.24 | ntpsec | 1.2.5-r0 | ALPINE-CVE-2026-18321 |
| Debian:12 | ntpsec | no fix listed | DEBIAN-CVE-2026-18321 |
| Debian:13 | ntpsec | no fix listed | DEBIAN-CVE-2026-18321 |
| Debian:14 | ntpsec | 1.2.5+dfsg-1 | DEBIAN-CVE-2026-18321 |
| Ubuntu:22.04:LTS | ntpsec | no fix listed | UBUNTU-CVE-2026-18321 |
| Ubuntu:24.04:LTS | ntpsec | no fix listed | UBUNTU-CVE-2026-18321 |
| Ubuntu:26.04:LTS | ntpsec | no fix listed | UBUNTU-CVE-2026-18321 |
| Ubuntu:26.10 | ntpsec | no fix listed | UBUNTU-CVE-2026-18321 |
Affected products (as reported)
Weakness: CWE-120 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H