Vulnerability in Nextcloud (CVE-2021-41177)

Summary

Vulnerability in Nextcloud (CVE-2021-41177). Confidential information can be exposed externally. Exploitable via AnonRateThrottle.

Original description

The description as published by the source.

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.

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2021-41177 has been found in Nextcloud.
Attackers can target a specific entry point like AnonRateThrottle over the network to misuse the product.
Confidential information can be exposed externally.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Nextcloud CVE-2021-41177" on the vendor's site.

CVE-2021-41177 (Nextcloud)
Attack vector: remote (network-reachable) / no user interaction
Attack surface: AnonRateThrottle / UserRateThrottle / config.php
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (unclassified) exists in Nextcloud. Attackers reach the vulnerable code path via AnonRateThrottle.

📍 Affected scope

Check the vendor advisory for the affected versions of Nextcloud. Attack surface: AnonRateThrottle / UserRateThrottle / config.php.

🔥 Severity

Severity: ?. Confidential information can be exposed externally.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Nextcloud' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
grep -r 'Nextcloud' . | grep -v node_modules
```
リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で Nextcloud を grep し、稼働しているサービス・バージョンを把握する。
2
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

References

advisory github.com
advisory security.gentoo.org
patch github.com
report hackerone.com