Vulnerability in github.com/cloudreve/Cloudreve/v4 (CVE-2026-77637)
Summary
Vulnerability in github.com/cloudreve/Cloudreve/v4 (CVE-2026-77637). Risk of unauthorized operations or information disclosure. Exploitable via POST /mail. Mitigation: upgrade to 4.0.0-20260715070110-bce08f88e9d8 or later.
Original description
The description as published by the source.
Summary
There is a privilege scope bypass in Cloudreve's admin API where two endpoints that mutate server state are missing the write-scope enforcement that their neighboring endpoints correctly apply. Specifically, the WOPI configuration fetch endpoint and the SMTP test/mail endpoint can both be triggered by an OAuth token that only has Admin.Read authorization — no Admin.Write needed. This breaks the intended OAuth scope boundary in a way that's subtle enough to have slipped through but meaningful enough to matter in a real deployment.
Details
The root cause is an inconsistency in how the admin tool routes are wired up in routers/router.go. The admin route group sets a baseline of ScopeAdminRead for everything underneath it (around line 868), and most write-capable endpoints inside the tool sub-group correctly layer on an additional RequiredScopes(types.ScopeAdminWrite) check on top of that. For example, the thumbnail executable setter (line 929) and the entity URL cache deletion (line 937) both do this properly.
The two endpoints that don't follow this pattern are tool.GET('wopi') (line 925) and tool.POST('mail') (line 933). Despite POST /mail clearly triggering an outbound email and GET /wopi fetching or probing WOPI service connectivity, neither has the ScopeAdminWrite guard. What that means in practice is that any OAuth application granted only Admin.Read — a scope that should be limited to inspecting configuration, not changing anything — ca…
Source: NIST National Vulnerability Database 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-2026-77637 has been found in github.com/cloudreve/Cloudreve/v4.
Attackers can target a specific entry point like POST /mail over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 3.8/10.
What to do: upgrade github.com/cloudreve/Cloudreve/v4 to 4.0.0-20260715070110-bce08f88e9d8 or later.
If unsure, ask your IT team or search "github.com/cloudreve/Cloudreve/v4 CVE-2026-77637" on the vendor's site.
CVE-2026-77637 (github.com/cloudreve/Cloudreve/v4) — CWE-862 / CVSS v3 3.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /mail / GET /wopi / ScopeAdminRead / tool
Patched: 4.0.0-20260715070110-bce08f88e9d8 — 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.
A vulnerability (CWE-862) exists in github.com/cloudreve/Cloudreve/v4. Attackers reach the vulnerable code path via POST /mail.
Check the vendor advisory for the affected versions of github.com/cloudreve/Cloudreve/v4. Attack surface: POST /mail / GET /wopi / ScopeAdminRead / tool.
Severity: Low (CVSS 3.8/10). Risk of unauthorized operations or information disclosure.
Update to 4.0.0-20260715070110-bce08f88e9d8.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /mail 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
-
1Identify 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。 -
2Hunt for indicators of compromise detect
grep 'POST /mail' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /mail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。 -
3Apply patch patch
Upgrade github.com/cloudreve/Cloudreve/v4 to 4.0.0-20260715070110-bce08f88e9d8ステージング環境で 4.0.0-20260715070110-bce08f88e9d8 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。
-
4Post-deployment verification verify
Replay attack against POST /mail 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
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com