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CVE-2026-58271 medium CVSS 6.8

Vulnerability in @sync-in/server (CVE-2026-58271)

Summary

Vulnerability in @sync-in/server (CVE-2026-58271). Confidential information can be exposed externally. Exploitable via POST /api/app/sync/register. Mitigation: upgrade to 2.4.0 or later.

Original description

The description as published by the source.

Affected component: Sync-in Server v2.3.0, POST /api/app/sync/register.

Required attacker capability: Valid login and password for a TOTP-enabled account with desktop sync permission.

Summary

POST /api/app/sync/register accepts credentials and a TOTP code to register a desktop sync client. In the vulnerable version, on a failed TOTP attempt, SyncClientsManager.register() called updateAccesses(user, ip, false), which hit a freeze branch that wrote passwordAttempts back unchanged. The counter never reached USER_MAX_PASSWORD_ATTEMPTS (10), so the account lockout gate never fired for repeated TOTP failures through this endpoint.

A successful TOTP guess registers a sync client and returns a {clientId, clientToken} pair, provided the account has the required desktop app permission and the registration payload is valid. The token can then be exchanged via POST /api/app/sync/auth/cookie for an authenticated session. While the guessed TOTP code is still valid, and because the attacker already knows the password, the attacker can also call POST /api/auth/2fa/disable to remove MFA.

Details

The endpoint is declared at sync.controller.ts line 71. @AuthTokenSkip() bypasses the bearer-token guard, so the route is reachable without any prior session:

@Post(SYNC_ROUTE.REGISTER)
@AuthTokenSkip()
register(@Body() syncClientRegistrationDto: SyncClientRegistrationDto, @Req() req: FastifyRequest): Promise {
  return this.syncClientsManager.re…

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-2026-58271 has been found in @sync-in/server.
Attackers can target a specific entry point like POST /api/app/sync/register over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 6.8/10.
What to do: upgrade @sync-in/server to 2.4.0 or later.
If unsure, ask your IT team or search "@sync-in/server CVE-2026-58271" on the vendor's site.

CVE-2026-58271 (@sync-in/server) — CWE-307 / CVSS v3 6.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /api/app/sync/register / POST /api/app/sync/auth/cookie / POST /api/auth/2fa/disable / POST /api/auth/login
Patched: 2.4.0 — 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

A vulnerability (CWE-307) exists in @sync-in/server. Attackers reach the vulnerable code path via POST /api/app/sync/register.

📍 Affected scope

Check the vendor advisory for the affected versions of @sync-in/server. Attack surface: POST /api/app/sync/register / POST /api/app/sync/auth/cookie / POST /api/auth/2fa/disable / POST /api/auth/login.

🔥 Severity

Severity: Medium (CVSS 6.8/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 2.4.0.

🛡️ 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/app/sync/register requests with malformed payloads or SQL meta-characters. Run grep -r '@sync-in/server' . 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 '@sync-in/server' . | 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 @sync-in/server 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/app/sync/register' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで POST /api/app/sync/register 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 @sync-in/server to 2.4.0

    ステージング環境で 2.4.0 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/app/sync/register 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

npm @sync-in/server
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.4.0"}]}]

References

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