The Nextcloud Android app is the Android client for Nextclou… (CVE-2021-43863)

Summary

Vulnerability reported (CVE-2021-43863). Confidential information can be exposed externally. Exploitable via FileContentProvider.

Original description

The description as published by the source.

The Nextcloud Android app is the Android client for Nextcloud, a self-hosted productivity platform. The Nextcloud Android app uses content providers to manage its data. Prior to version 3.18.1, the providers FileContentProvider and DiskLruImageCacheFileProvider have security issues (an SQL injection, and an insufficient permission control, respectively) that allow malicious apps in the same device to access Nextcloud's data bypassing the permission control system. Users should upgrade to version 3.18.1 to receive a patch. There are no known workarounds aside from upgrading.

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-2021-43863 has been found.
Attackers can target a specific entry point like FileContentProvider 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 "CVE-2021-43863" on the vendor's site.

CVE-2021-43863
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: FileContentProvider / DiskLruImageCacheFileProvider
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) has been reported. Attackers reach the vulnerable code path via FileContentProvider without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions. Attack surface: FileContentProvider / DiskLruImageCacheFileProvider.

🔥 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. Audit SBOM/dependencies to find affected services.

Response actions

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

1
Identify exposure identify
```
Audit SBOM/dependencies for affected components.
```
資産台帳・SBOM・依存マニフェストで影響コンポーネントを特定する。
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
patch github.com
report hackerone.com