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Fencer Vulns
high 8.1

CVE-2021-41177 json

Rate-limits not working on instances without configured memory cache backend

published 2021-10-25 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-28279

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known

Summary

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`.

Patch / fix

  • nextcloud nextcloud_server 20.0.13, 21.0.5, 22.2.0
  • nextcloud Package Hub 15 SP3, Package Hub 15 SP2, Package Hub 15 SP1 +3 more 20.0.14-bp153.2.9.1

opensuse advisories openSUSE-SU-2021:1602-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-41177 updated cvss 8.1

nextcloud: rate-limits not working on instances without configured memory cache backend

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.55% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
NVD 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
NVD 2.0 5.5 AV:N/AC:L/Au:S/C:P/I:N/A:P

Affected products

  • nextcloud security-advisories

Classification

Weakness
  • CWE-799 Improper Control of Interaction Frequency

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.