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Vulnerability record · CVE-2021-22212 · published 8 June 2021

CVE-2021-22212: Ntpsec broken cryptographic algorithm vulnerability

Ntpsec · Ntpsec

ntpkeygen can generate keys that ntpd fails to parse. NTPsec 1.2.0 allows ntpkeygen to generate keys with '#' characters. ntpd then either pads, shortens the key, or fails to load these keys entirely, depending on the key type and the placement of the '#'. This results in the administrator not being able to use the keys as expected or the keys are shorter than expected and easier to brute-force, possibly resulting in MITM attacks between ntp clients and ntp servers. For short AES128 keys, ntpd generates a warning that it is padding them.

7.4 CVSS 3.1 High EPSS 0.52% · top 58.0% CWE-327 · Broken cryptographic algorithm
7.4CVSS 3.1 base score, v2 5.8
0.52%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
8References
17 Jun 2026Last modified by NVD

Description

ntpkeygen can generate keys that ntpd fails to parse. NTPsec 1.2.0 allows ntpkeygen to generate keys with '#' characters. ntpd then either pads, shortens the key, or fails to load these keys entirely, depending on the key type and the placement of the '#'. This results in the administrator not being able to use the keys as expected or the keys are shorter than expected and easier to brute-force, possibly resulting in MITM attacks between ntp clients and ntp servers. For short AES128 keys, ntpd generates a warning that it is padding them.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugzilla.redhat.com/show_bug.cgi?id=1955859 Issue TrackingPatchThird Party Advisory
https://gitlab.com/NTPsec/ntpsec/-/issues/699 Issue TrackingPatchThird Party Advisory
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-22212.json Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3GIT2HYL5BQXPGKI6ZDNG47
https://bugzilla.redhat.com/show_bug.cgi?id=1955859 Issue TrackingPatchThird Party Advisory
https://gitlab.com/NTPsec/ntpsec/-/issues/699 Issue TrackingPatchThird Party Advisory
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-22212.json Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3GIT2HYL5BQXPGKI6ZDNG47

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Source: NIST National Vulnerability Database (record CVE-2021-22212), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.