CVE-2021-22915

mediumpriority · track · 40EPSS 0.017 · 78 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.74% (78th) EPSS

CVSS 5 · medium

Is it mine?

6 products

Check your exposure

Who says so?

3 sources

cnnvd · enisa_euvd · nvd

EPSS · scored 2026-10-27

Nextcloud server before 19.0.11, 20.0.10, 21.0.2 is vulnerable to brute force attacks due to lack of inclusion of IPv6 subnets in rate-limiting considerations. This could potentially result in an attacker bypassing rate-limit controls such as the Nextcloud brute-force protection.

cvss

Technical severity, 0–10. One row per scoring source.

9.8

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–critical · 5–9.8

v2.05mediumAV:N/AC:L/Au:N/C:P/I:N/A:Nprimary · NVD / NIST USexploitability 10 · impact 2.9

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 5.9

v3.19criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-307USprimary

affected products (6)

Products and version ranges known to be affected.

n/a Nextcloud Server≤ Fixed in 19.0.11, 20.0.10, 21.0.2enisa_euvdEU
fedoraproject fedora= 33nvdUScpe:2.3:o:fedoraproject:fedora:*:*:*:*:*:*:*:*
fedoraproject fedora= 34nvdUScpe:2.3:o:fedoraproject:fedora:*:*:*:*:*:*:*:*
nextcloud nextcloud server< 19.0.11nvdUScpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:*
nextcloud nextcloud server20.0.0 → 20.0.10nvdUScpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:*
nextcloud nextcloud server21.0.0 → 21.0.2nvdUScpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:*

also known as (2)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd NVD CVE.org MITRE

published 2021-06-11modified 2026-06-17

related (825)

Related entries.

ID	severity	EPSS	exploitable	published
CVE-2019-17240US	critical9.8	39.6% (99th)	Exploit	2019-10-06
bl-kernel/security.class.php in Bludit 3.9.2 allows attackers to bypass a brute-force protection mechanism by using many different forged X-Forwarded-For or Client-IP HTTP headers.
CVE-2020-15906US	critical9.8	27.2% (98th)	Exploit	2020-10-22
tiki-login.php in Tiki before 21.2 sets the admin password to a blank value after 50 invalid login attempts.
CVE-2016-9361US	critical9.8	20.4% (97th)	Exploit	2017-02-13
An issue was discovered in Moxa NPort 5110 versions prior to 2.6, NPort 5130/5150 Series versions prior to 3.6, NPort 5200 Series versions prior to 2.8, NPort 5400 Series versions…
CVE-2003-1096US	high10.0	10.5% (96th)	Exploit	2003-12-31
The Cisco LEAP challenge/response authentication mechanism uses passwords in a way that is susceptible to dictionary attacks, which makes it easier for remote attackers to gain pri…
CVE-2023-27100US	critical9.8	9.84% (96th)	Exploit	2023-03-22
Improper restriction of excessive authentication attempts in the SSHGuard component of Netgate pfSense Plus software v22.05.1 and pfSense CE software v2.6.0 allows attackers to byp…

+820 more

references (12)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan