CVE-2021-22212

Severity: high (CVSS 7.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-06-08 · updated 2026-06-17
Weakness: CWE-327

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.

Affected products

Fedoraproject Fedora: 34
ntpsec: 1.2.0

References

https://bugzilla.redhat.com/show_bug.cgi?id=1955859
https://gitlab.com/NTPsec/ntpsec/-/issues/699
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-22212.json
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3GIT2HYL5BQXPGKI6ZDNG473IEQ5WQF2/
https://bugzilla.redhat.com/show_bug.cgi?id=1955859
https://gitlab.com/NTPsec/ntpsec/-/issues/699
https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-22212.json
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3GIT2HYL5BQXPGKI6ZDNG473IEQ5WQF2/

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