No exploitation reportedFix available

CVE-2021-41177

Q: Is CVE-2021-41177 actively exploited?

Active exploitation of CVE-2021-41177 has not been confirmed. Its EPSS score was 1.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-41177?

CVE-2021-41177 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H.

No exploitation reported by the sources we read.

Published2021-10-25
Fixed in22.2.0 · 21.0.5 · 20.0.13
WeaknessCWE-799

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Nextcloud is an open-source, self-hosted productivity platform. Prior to versions 20.0.13, 21.0.5, and 22.2.0, Nextcloud Server did not implement a database backend for rate-limiting purposes. Any component of Nextcloud using rate-limits (as as `AnonRateThrottle` or `UserRateThrottle`) was thus not rate limited on instances not having a memory cache backend configured. In the case of a default installation, this would notably include the rate-limits on the two factor codes. It is recommended that the Nextcloud Server be upgraded to 20.0.13, 21.0.5, or 22.2.0. As a workaround, enable a memory cache backend in `config.php`.

Timeline

dates in UTC

2021-10-2522:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-41177?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-41177?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Nextcloud nextcloud server

Branch	Affected	Fixed in	Source
22.x	≥ 22.0.0, < 22.2.0	22.2.0	NVD
21.0	≥ 21.0.0, < 21.0.5	21.0.5	NVD
20.0	< 20.0.13	20.0.13	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Nextcloud nextcloud server to 22.2.0 · 21.0.5 · 20.0.13

Advisories and patches

github.comPatch

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CNACVSS 3.18.1read 2026-10-23
NVDCVSS 3.18.1read 2026-10-23
NVDCVSS 2.05.5read 2026-10-23
CNAweakness (CWE)CWE-799read 2026-10-23
FIRST EPSSEPSS score1.6 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Published: 2021-10-25
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-41177?

Is CVE-2021-41177 actively exploited?

Active exploitation of CVE-2021-41177 has not been confirmed. Its EPSS score was 1.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-41177?

CVE-2021-41177 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H.

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