# CVE-2026-121505: Out-of-bounds Read in NTPsec

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

An out-of-bounds read in the NTS-KE client response parser (nts_client_process_response_core) in NTPsec before 1.2.4 allows a malicious NTS-KE server to read the client's stack memory, including pointers that defeat ASLR, which the client then sends in cleartext as NTS cookies, via an NTS-KE record whose declared length exceeds the data received.

## Remediation

- fix: Upgrade to version 1.2.4 or above. (source: CNA: GitLab)

## Affected products and versions

- NTPsec / NTPsec: ≥ 1.1.4; < 1.2.4 (affected, semver). Source: CNA: GitLab

## Severity and prioritization

- CVSS 3.1: 3.7 (low); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N; source: CNA: GitLab

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-125

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://gitlab.com/NTPsec/ntpsec/-/commit/caf0eb5df3c6ddbfc2941389bff0f9146835c021 (CNA: GitLab)

- https://gitlab.com/NTPsec/ntpsec/-/work_items/836 (CNA: GitLab)

- https://gitlab.com/NTPsec/ntpsec/-/work_items/902 (CNA: GitLab)

## Provenance

- CNA: GitLab: https://www.cve.org/CVERecord?id=CVE-2026-121505; retrieved 2026-11-03; source updated 2026-11-03

Revision: d220d299ce95763daf85448c5263a9832524d99b50cae8313e35c2a2c727cf8c

Canonical: https://y2.dev/cve/CVE-2026-121505

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