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CVE-2026-62323 medium CVSS 6.3

Authorization Flaw in github.com/cloudreve/Cloudreve/v4 (CVE-2026-62323)

Summary

Vulnerability in github.com/cloudreve/Cloudreve/v4 (CVE-2026-62323). Data can be tampered with by attackers. Exploitable via PUT /api/v4/file/viewerSession. Mitigation: upgrade to 4.0.0-20260626022433-f3347130ac48 or later.

Original description

The description as published by the source.

Summary

Cloudreve WOPI access tokens are generated as ., but the WOPI middleware validates only the session id prefix and never compares the supplied token to the stored token. In addition, a WOPI viewer session does not store or enforce the requested viewer action. A session created for a view or preview action can still call WOPI write routes if the underlying file is writable by the session user.

Impact

A WOPI integration that is only expected to view a user's file can modify that file through the WOPI write endpoints. If the WOPI URL or session id leaks, the random token suffix does not protect the session because any suffix is accepted for an existing session id.

This affects deployments that configure WOPI viewers for user files. The attacker primitive is strongest when a malicious or compromised WOPI viewer receives a view-only URL and then writes content back to Cloudreve.

Affected version

Verified in source and runtime on latest master commit ba2e870bbd17f1918dd2321de861e453f696d6a3 and latest observed tag 4.16.1.

Technical details

Cloudreve creates WOPI viewer sessions in pkg/filemanager/manager/viewer.go:

sessionID := uuid.Must(uuid.NewV4()).String()
token := util.RandStringRunesCrypto(128)
sessionCache := &ViewerSessionCache{
    ID:       sessionID,
    Uri:      file.Uri(false).String(),
    UserID:   m.user.ID,
    ViewerID: viewer.ID,
    FileID:   file.ID(),
    Version:  version,
    Token:    fmt.Sprintf("%s.%s", sessionID…

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-2026-62323 has been found in github.com/cloudreve/Cloudreve/v4.
Attackers can target a specific entry point like PUT /api/v4/file/viewerSession over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 6.3/10.
What to do: upgrade github.com/cloudreve/Cloudreve/v4 to 4.0.0-20260626022433-f3347130ac48 or later.
If unsure, ask your IT team or search "github.com/cloudreve/Cloudreve/v4 CVE-2026-62323" on the vendor's site.

CVE-2026-62323 (github.com/cloudreve/Cloudreve/v4) — CWE-863 / CVSS v3 6.3
Attack vector: remote (network-reachable)
Attack surface: PUT /api/v4/file/viewerSession / GET /api/v4/file/wopi/4xc5 / GET /api/v4/file/wopi/4xc5/contents / POST /api/v4/file/wopi/4xc5/contents
Patched: 4.0.0-20260626022433-f3347130ac48 — 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 PUT /api/v4/file/viewerSession.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/cloudreve/Cloudreve/v4. Attack surface: PUT /api/v4/file/viewerSession / GET /api/v4/file/wopi/4xc5 / GET /api/v4/file/wopi/4xc5/contents / POST /api/v4/file/wopi/4xc5/contents.

🔥 Severity

Severity: Medium (CVSS 6.3/10). Data can be tampered with by attackers.

🔧 How to fix

Update to 4.0.0-20260626022433-f3347130ac48.

🛡️ 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 PUT /api/v4/file/viewerSession 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 'PUT /api/v4/file/viewerSession' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで PUT /api/v4/file/viewerSession 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 4.0.0-20260626022433-f3347130ac48

    ステージング環境で 4.0.0-20260626022433-f3347130ac48 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 PUT /api/v4/file/viewerSession 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":"4.0.0-20260626022433-f3347130ac48"}]}]
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

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