YunaiV yudao-cloud Improper Authentication Vulnerability (CVE-2026-7679)

A critical security vulnerability, identified as CVE-2026-7679, affects YunaiV yudao-cloud software up to version 2026.01. The vulnerability resides within the getAccessToken function of the yudao-module-system-biz/src/main/java/io/github/ruoyi/common/oauth2/service/impl/OAuth2TokenServiceImpl.java file. Successful exploitation allows remote attackers to perform unauthorized actions due to improper authentication mechanisms. The exploit is publicly available, raising the risk of widespread exploitation. The vendor was notified but did not respond, leaving users vulnerable. This vulnerability poses a significant risk to organizations using affected versions of yudao-cloud.

Attack Chain

1. Attacker identifies a vulnerable instance of YunaiV yudao-cloud (<= 2026.01) exposed to the internet.
2. Attacker crafts a malicious request targeting the getAccessToken function within OAuth2TokenServiceImpl.java.
3. The crafted request exploits the improper authentication flaw in the getAccessToken function.
4. The vulnerable function fails to properly validate the attacker's request.
5. The attacker bypasses authentication and gains unauthorized access.
6. Attacker leverages the unauthorized access to perform privileged actions, potentially including data modification or exfiltration.
7. The attacker could establish persistent access by creating rogue administrator accounts.

Impact

Successful exploitation of CVE-2026-7679 can lead to a complete compromise of the YunaiV yudao-cloud application. An attacker can gain unauthorized access to sensitive data, modify critical configurations, or disrupt services. Given that the exploit is publicly available, the risk of widespread exploitation is elevated. This could result in significant financial losses, reputational damage, and legal liabilities for affected organizations.

Recommendation

• Apply available patches or upgrade to a secure version of YunaiV yudao-cloud that addresses CVE-2026-7679 immediately.
• Monitor web server logs for suspicious requests targeting the getAccessToken function in OAuth2TokenServiceImpl.java using the provided Sigma rule.
• Implement strict input validation and authentication mechanisms in the getAccessToken function to prevent similar vulnerabilities in the future.
• Review and restrict network access to the yudao-cloud application, limiting access to authorized users and systems.