CVE-2026-58269: CWE-288: Authentication Bypass Using an Alternate Path or Channel in Sync-in server
CVE-2026-58269 is an authentication bypass vulnerability in Sync-in Server versions prior to 2.4.0. The issue occurs because the `POST /api/auth/token` endpoint does not enforce two-factor authentication (2FA) when issuing JWT tokens, allowing attackers with stolen credentials to bypass 2FA. The parallel login endpoint correctly enforces 2FA. The vulnerability is patched in version 2.4.0.
AI Analysis
Technical Summary
Sync-in Server before version 2.4.0 has an authentication bypass vulnerability (CWE-288) due to the `POST /api/auth/token` endpoint returning full access and refresh JWT tokens without verifying if the user has TOTP 2FA enabled. This allows an attacker who has obtained valid username and password credentials to bypass 2FA protections by using this endpoint. The `POST /api/auth/login` endpoint correctly enforces 2FA by checking the `user.twoFaEnabled` flag before setting authentication cookies. The issue is fixed in version 2.4.0.
Potential Impact
An attacker with stolen or phished credentials can bypass two-factor authentication and gain full access tokens, potentially leading to unauthorized access to user accounts and sensitive data. The vulnerability affects confidentiality and integrity but does not impact availability. The CVSS 3.1 score is 8.1 (high severity) with network attack vector, low attack complexity, and no user interaction required.
Mitigation Recommendations
Upgrade Sync-in Server to version 2.4.0 or later, where the authentication bypass vulnerability is patched. No other mitigations are specified or required as the fix is official and addresses the root cause.
CVE-2026-58269: CWE-288: Authentication Bypass Using an Alternate Path or Channel in Sync-in server
Description
CVE-2026-58269 is an authentication bypass vulnerability in Sync-in Server versions prior to 2.4.0. The issue occurs because the `POST /api/auth/token` endpoint does not enforce two-factor authentication (2FA) when issuing JWT tokens, allowing attackers with stolen credentials to bypass 2FA. The parallel login endpoint correctly enforces 2FA. The vulnerability is patched in version 2.4.0.
CVSS v3.1
Score 8.1high
Affected software
Sync-in
server
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Sync-in Server before version 2.4.0 has an authentication bypass vulnerability (CWE-288) due to the `POST /api/auth/token` endpoint returning full access and refresh JWT tokens without verifying if the user has TOTP 2FA enabled. This allows an attacker who has obtained valid username and password credentials to bypass 2FA protections by using this endpoint. The `POST /api/auth/login` endpoint correctly enforces 2FA by checking the `user.twoFaEnabled` flag before setting authentication cookies. The issue is fixed in version 2.4.0.
Potential Impact
An attacker with stolen or phished credentials can bypass two-factor authentication and gain full access tokens, potentially leading to unauthorized access to user accounts and sensitive data. The vulnerability affects confidentiality and integrity but does not impact availability. The CVSS 3.1 score is 8.1 (high severity) with network attack vector, low attack complexity, and no user interaction required.
Mitigation Recommendations
Upgrade Sync-in Server to version 2.4.0 or later, where the authentication bypass vulnerability is patched. No other mitigations are specified or required as the fix is official and addresses the root cause.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-29T21:54:30.332Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ab190cb55bf5e2cf5693c8d
Added to database: 09/21/2026, 20:17:15 UTC
Last enriched: 09/21/2026, 20:31:28 UTC
Last updated: 09/21/2026, 20:48:38 UTC
Views: 5
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