SQLi, XSS, and SSRF: Breaking Down Zimbra’s Latest Security Threats | Cyble

Overview

Zimbra Collaboration Suite (ZCS) is a widely used email and collaboration platform. Security remains a top priority for administrators and users who rely on Zimbra for business communication. Recently, Zimbra has addressed several critical security issues, including stored cross-site scripting (XSS), SQL injection (SQLi), and server-side request forgery (SSRF).

This article provides a detailed technical breakdown of these vulnerabilities, their potential impact, and recommended actions.

Below is an in-depth analysis of these vulnerabilities.

1. Stored Cross-Site Scripting (XSS) – CVE-2025-27915

• Affected Versions: ZCS 9.0, 10.0, and 10.1 (before patches 44, 10.0.13, and 10.1.5)
• Patch Availability: Fixed in the latest patches
• Description:
  • This vulnerability resides in the Classic Web Client due to insufficient sanitization of HTML content in ICS calendar invite files.
  • Attackers can embed malicious JavaScript inside an ICS file, which executes when a victim opens an email containing the ICS entry.
  • Exploitation allows unauthorized actions within the victim’s session, such as modifying email filters to redirect messages to an attacker’s inbox.
• Impact:
  • Unauthorized email forwarding
  • Credential theft via session hijacking
  • Potential phishing and further exploitation
• Mitigation & Remediation:
  • Upgrade to the latest Zimbra patch immediately.
  • Implement strict input validation and content sanitization policies.
  • Restrict the execution of embedded JavaScript within email content.

2. SQL Injection (SQLi) – CVE-2025-25064

• Affected Versions: Zimbra Collaboration 10.0.x before 10.0.12 and 10.1.x before 10.1.4
• Patch Availability: Fixed in the latest patches
• Description:
  • The vulnerability exists in the ZimbraSyncService SOAP endpoint, where insufficient input validation allows attackers to manipulate query parameters.
  • Authenticated attackers can inject malicious SQL commands into database queries.
  • The exploitation of this flaw could allow attackers to retrieve email metadata from the database.
• Impact:
  • Data exfiltration, including email records
  • Potential unauthorized access to sensitive database information
  • Increased risk of privilege escalation and lateral movement within the system
• Mitigation & Remediation:
  • Upgrade to the latest Zimbra patch immediately.
  • Apply parameterized queries to prevent SQL injection.
  • Implement web application firewalls (WAF) to detect and block SQLi attempts.

3. Server-Side Request Forgery (SSRF) – CVE-2025-25065

• Affected Versions: Zimbra Collaboration 9.0.0 before Patch 43, 10.0.x before 10.0.12, and 10.1.x before 10.1.4
• Patch Availability: Fixed in the latest patches
• Description:
  • The vulnerability is in the RSS feed parser, where an attacker can manipulate RSS feed URLs to force the server to make unauthorized requests.
  • This flaw allows attackers to redirect Zimbra servers to internal network endpoints, potentially exposing sensitive internal resources.
• Impact:
  • Internal service enumeration via SSRF
  • Possible access to internal API endpoints
  • Increased attack surface for further exploitation
• Mitigation & Remediation:
  • Upgrade to the latest Zimbra patch immediately.
  • Restrict outbound requests to untrusted URLs.
  • Use network segmentation and access control policies to prevent unauthorized internal access.

General Recommendations for Zimbra Administrators

To maintain a secure Zimbra deployment, follow these best practices:

1. Regularly Update Software: Keep Zimbra updated with the latest security patches.
2. Monitor Logs and Alerts: Enable logging and analyze logs for signs of exploitation attempts.
3. Harden Authentication Mechanisms:
   • Implement multi-factor authentication (MFA) for administrator and user accounts.
   • Enforce strong password policies.
4. Restrict Privileges: Limit user access to necessary functions and avoid granting unnecessary permissions.
5. Use Web Application Firewalls (WAFs): Deploy WAFs to filter malicious requests and prevent attacks.
6. Security Awareness Training: Educate employees on security threats like phishing and social engineering.
7. Regularly Back Up Data: Ensure backups are performed and stored securely to prevent data loss in case of an attack.

Conclusion

The recently discovered vulnerabilities in the Zimbra Collaboration Suite reinforce the importance of proactive security management. Administrators must promptly apply patches, monitor for indicators of compromise, and implement best security practices to protect against emerging threats.

Organizations can mitigate risks and safeguard their communication infrastructure by staying informed through Zimbra’s advisory channels and following recommended security measures.

References:

• Zimbra Security Advisories – Zimbra :: Tech Center
• NVD – CVE-2025-25064
• NVD – CVE-2025-25065
• NVD – CVE-2025-27915