Sign in Sign up
JA · EN · FR
SecPulse
Categories
CVE-2026-55502 high CVSS 7.1

Authorization Flaw in github.com/cloudreve/Cloudreve/v4 (CVE-2026-55502)

Summary

Vulnerability in github.com/cloudreve/Cloudreve/v4 (CVE-2026-55502). Data can be tampered with by attackers. Exploitable via POST /api/v4/admin/policy/oauth/signin. Mitigation: upgrade to 4.17.0 or later.

Original description

The description as published by the source.

Summary

Cloudreve 4.16.1 has an OAuth scope authorization bypass in the admin storage policy routes. An OAuth bearer token scoped to Admin.Read but not Admin.Write can call POST /api/v4/admin/policy/oauth/signin and update OneDrive storage policy credentials.

The route is inside the admin group that requires Admin.Read, but it does not add the local Admin.Write guard used by sibling policy mutation routes. Its handler persists attacker-supplied secret and app_id values into the selected OneDrive storage policy before returning an OAuth URL.

Impact

An OAuth application that was granted only read-only admin scope can modify persistent storage backend configuration for a OneDrive policy. This can break the storage backend, replace the stored application secret and app ID, and redirect future OAuth setup for that policy to attacker-controlled application parameters. The attack crosses the intended OAuth scope boundary because Admin.Write is required for sibling storage policy mutation routes.

Reproduction

Preconditions:

  1. The instance has a OneDrive storage policy.
  2. An admin user authorizes an OAuth client for Admin.Read but not Admin.Write.
  3. The OAuth client obtains a bearer access token for that admin user.

Send the following request with that read-only admin scoped token:

POST /api/v4/admin/policy/oauth/signin HTTP/1.1
Authorization: Bearer 
Content-Type: application/json

{"id":1,"secret":"attacker-secret","app_id":"attacker-…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

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-2026-55502 has been found in github.com/cloudreve/Cloudreve/v4.
Attackers can target a specific entry point like POST /api/v4/admin/policy/oauth/signin over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 7.1/10.
What to do: upgrade github.com/cloudreve/Cloudreve/v4 to 4.17.0 or later.
If unsure, ask your IT team or search "github.com/cloudreve/Cloudreve/v4 CVE-2026-55502" on the vendor's site.

CVE-2026-55502 (github.com/cloudreve/Cloudreve/v4) — CWE-863 / CVSS v3 7.1
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /api/v4/admin/policy/oauth/signin / Admin.Read / Admin.Write / secret
Patched: 4.17.0 — apply immediately
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

Incorrect authorization (CWE-863) exists in github.com/cloudreve/Cloudreve/v4. Attackers reach the vulnerable code path via POST /api/v4/admin/policy/oauth/signin.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/cloudreve/Cloudreve/v4. Attack surface: POST /api/v4/admin/policy/oauth/signin / Admin.Read / Admin.Write / secret.

🔥 Severity

Severity: High (CVSS 7.1/10). Data can be tampered with by attackers.

🔧 How to fix

Update to 4.17.0.

🛡️ 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 POST /api/v4/admin/policy/oauth/signin requests with malformed payloads or SQL meta-characters. Run grep -r 'github.com/cloudreve/Cloudreve/v4' . 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. 1
    Identify exposure identify 
    grep -r 'github.com/cloudreve/Cloudreve/v4' . | 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 github.com/cloudreve/Cloudreve/v4 を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Hunt for indicators of compromise detect 
    grep 'POST /api/v4/admin/policy/oauth/signin' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで POST /api/v4/admin/policy/oauth/signin への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。

  3. 3
    Apply patch patch 
    Upgrade github.com/cloudreve/Cloudreve/v4 to 4.17.0

    ステージング環境で 4.17.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。

  4. 4
    Post-deployment verification verify 
    Replay attack against POST /api/v4/admin/policy/oauth/signin on staging to confirm patch closes the vector

    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 Step 2 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

go github.com/cloudreve/Cloudreve/v4
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.17.0"}]}]
go github.com/cloudreve/Cloudreve/v3
[{"type":"SEMVER","events":[{"introduced":"0"},{"last_affected":"3.0.0-20250225100611-da4e44b77af4"}]}]
Go github.com/cloudreve/Cloudreve
[{"type":"SEMVER","events":[{"introduced":"0"}]}]

References

We use cookies for analytics and ad measurement. This setting applies to all Game co., Ltd. sites. Details