CVE-2021-22212 [Medium] | Security Vulnerability in 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.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.14%	0.52%	+0.38%
2	2025-06-05	0.04%	0.14%	+0.10%
3	2025-03-30	—	0.04%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.14%

0.52%

+0.38%

2025-06-05

0.04%

0.14%

+0.10%

2025-03-30

—

0.04%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
4.0	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:H) They need powerful rights—admin, root, or similar—before this pays off. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	0.3	3.6	[email protected]
7.4	3.1	HIGH	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	2.2	5.2	[email protected]
5.8	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:P/I:P/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:N) No availability impact.	8.6	4.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

4.0

3.1

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N Click to expand

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H): They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

0.3

3.6

[email protected]

7.4

3.1

HIGH

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

2.2

5.2

[email protected]

5.8

2.0

MEDIUM

AV:N/AC:M/Au:N/C:P/I:P/A:N Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:M): Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:N): No availability impact.

8.6

4.9

[email protected]

OS Trackers for CVE-2021-22212

vendor	priority	summary	link
`alpine`	high	CVE-2021-22212: 1 source package rows (ntpsec); 7 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 0.	https://security.alpinelinux.org/vuln/CVE-2021-22212
`debian`	not yet assigned	CVE-2021-22212 not yet assigned priority: Debian including 1 source packages (ntpsec), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2021-22212
`ubuntu`	low	CVE-2021-22212 low priority: Ubuntu including 1 source packages (ntpsec), 14 status rows across 14 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, trusty, upstream, xenial): ignored 7, not-affected 5, DNE 1, released 1.	https://ubuntu.com/security/CVE-2021-22212

Affected software / configurations for CVE-2021-22212

Vendor	Product	Version	Raw CPE
ntpsec	ntpsec	1.2.0	cpe:2.3:a:ntpsec:ntpsec:1.2.0:::::::*
fedoraproject	fedora	34	cpe:2.3:o:fedoraproject:fedora:34:::::::*

References for CVE-2021-22212

URL	Tags
https://bugzilla.redhat.com/show_bug.cgi?id=1955859	Issue Tracking Patch Third Party Advisory
https://gitlab.com/NTPsec/ntpsec/-/issues/699	Issue Tracking Patch Third 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/3GIT2HYL5BQXPGKI6ZDNG473IEQ5WQF2/

URL

CVE-2021-22212

Exploit prediction scoring system (EPSS) score for CVE-2021-22212

Common vulnerability scoring system (CVSS) metrics for CVE-2021-22212

Weakness enumeration for CVE-2021-22212

OS Trackers for CVE-2021-22212

Affected software / configurations for CVE-2021-22212

References for CVE-2021-22212