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VulnerabilityPublished

CVE-2026-121506: NTPsec · Out-of-bounds Write

Affects NTPsecSource CVE Database V5

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Not known to be exploited · CVSS 7.4 High : upgrade to 1.2.5 soon.

Data as of 3 Nov 2026, 15:58 UTC

CVSS 3.1 base score
7.4High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitLab)CVSS 3.17.4
Patch
Available – fixed in 1.2.5
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.

What to do

Upgrade NTPsec and ntpsec/ntpsec to 1.2.5.

Affected software

ProductAffectedFixed in
NTPsecNTPsecAffected
  • >=1.1.4 <1.2.5
Fixed in
  • 1.2.5
GitHubntpsec/ntpsecpkg:github/ntpsec/ntpsecOther threatsAffected
  • >=1.1.4 <1.2.5
Fixed in
  • 1.2.5

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade NTPsec to version 1.2.5 or later, where this vulnerability is fixed. No other mitigation is required as the vendor has provided an official fix.

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.

References

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