A significant security flaw has been identified in Zimbra Collaboration Server (ZCS), a widely used open-source email and collaboration platform. This vulnerability, designated as CVE-2025-32354, affects versions 9.0 through 10.1 and enables attackers to perform unauthorized operations via the GraphQL endpoint, potentially compromising sensitive user information.
Understanding the Vulnerability
The core of this issue lies in the GraphQL API endpoint located at `/service/extension/graphql` within Zimbra’s webmail interface. Due to inadequate validation of Cross-Site Request Forgery (CSRF) tokens, malicious actors can deceive authenticated users into executing unintended actions. CSRF attacks exploit the trust a web application places in a user’s browser session. In this scenario, the absence of proper anti-CSRF measures allows attackers to craft malicious web pages or emails that, when accessed by a logged-in Zimbra user, can submit unauthorized requests on their behalf.
Potential Exploits and Risks
By leveraging this vulnerability, attackers can:
– Modify or export user contacts.
– Alter account settings, such as email forwarding rules.
– Access and exfiltrate sensitive data, including email metadata and folder structures.
The severity of this flaw is heightened by the fact that Zimbra’s GraphQL API can execute high-privilege operations without requiring additional authentication checks. A proof-of-concept exploit demonstrated that a single malicious HTTP POST request could compromise an account if the victim visits a malicious page while authenticated.
Affected Versions and Mitigation Strategies
Zimbra has confirmed that all ZCS releases from version 9.0 up to 10.1.3 are susceptible to this vulnerability. To address the issue, patches have been released in ZCS version 10.1.4, which enforces CSRF token validation for all GraphQL requests.
For administrators unable to immediately upgrade, the following mitigation measures are recommended:
– Disable GraphQL’s GET Method: Utilize the `zimbra_gql_enable_dangerous_deprecated_get_method_will_be_removed` local configuration parameter to disable the GET method in GraphQL.
– Implement Reverse Proxy Rules: Set up rules to block unauthorized GraphQL mutations, thereby preventing malicious operations.
– User Education: Inform users about the risks of clicking on untrusted links while authenticated, as this can trigger CSRF attacks.
Zimbra’s advisory emphasizes the critical nature of this vulnerability, stating that CSRF vulnerabilities in mission-critical email systems create lateral movement opportunities in enterprise networks.
Broader Implications and Related Vulnerabilities
This CSRF vulnerability is part of a series of security issues identified in Zimbra Collaboration Server. For instance, CVE-2024-45519 is a critical remote code execution (RCE) vulnerability in Zimbra’s postjournal service, which allows unauthenticated remote command execution. This flaw has been actively exploited, with attackers sending malicious emails to execute commands on vulnerable servers. The postjournal service is not enabled by default, but its presence on certain servers has led to widespread exploitation attempts. ([cyble.com](https://cyble.com/blog/zimbra-remote-code-execution-vulnerability-under-active-attack/?utm_source=openai))
Another notable vulnerability, CVE-2024-9665, involves a CSRF flaw in Zimbra’s GraphQL implementation, allowing remote attackers to disclose sensitive information. Exploitation requires user interaction, such as opening a malicious email, and results from inadequate protections against CSRF attacks. ([nvd.nist.gov](https://nvd.nist.gov/vuln/detail/CVE-2024-9665?utm_source=openai))
These vulnerabilities underscore the importance of promptly applying security patches and implementing robust security measures to protect against potential exploits.
Recommendations for Administrators
Given the critical nature of these vulnerabilities, administrators are urged to:
– Apply Patches Promptly: Ensure that all Zimbra servers are updated to the latest versions to mitigate known vulnerabilities.
– Review Configurations: Verify that services like postjournal are disabled if not in use and that configurations do not expose the system to unnecessary risks.
– Monitor for Unusual Activity: Implement monitoring solutions to detect anomalous behavior that may indicate exploitation attempts.
– Educate Users: Conduct training sessions to raise awareness about phishing attacks and the importance of cautious behavior when interacting with emails and web links.
By taking these proactive steps, organizations can enhance their security posture and reduce the risk of unauthorized access and data breaches.
Conclusion
The discovery of the CSRF vulnerability in Zimbra’s GraphQL endpoint highlights the ongoing challenges in securing web applications against sophisticated attacks. As enterprises increasingly rely on APIs for integration and functionality, rigorous security testing and prompt patching become essential components of a comprehensive cybersecurity strategy. Administrators must remain vigilant, apply updates without delay, and educate users to maintain a secure and resilient infrastructure.
