VMware ESXi and vCenter Server contain a reflected cross-site scripting vulnerability due to improper input validation. A malicious actor with network access to the login page of certain ESXi host or vCenter Server URL paths may exploit this issue to steal cookies or redirect to malicious websites. This vulnerability has a CVSS score of 4.3, indicating a medium severity level. Organizations using these products should be aware of the potential risks associated with this vulnerability.
Given the nature of the vulnerability, risk to organizations includes potential unauthorized access to sensitive information and disruption of services. Attackers may leverage this vulnerability to perform actions such as cookie theft or redirection to harmful sites, thereby impacting the confidentiality of user data.
Currently, there is known exploit information available, which emphasizes the urgency for organizations to address this vulnerability in their systems. Organizations should prioritize patching immediately to safeguard their environments against potential exploitation.
As the situation develops, it is crucial for defenders to stay informed and apply necessary remediations to mitigate the risk associated with this vulnerability.
Vulnerability Details
VMware ESXi and vCenter Server contain a reflected cross-site scripting vulnerability due to improper input validation. A malicious actor with network access to the login page of certain ESXi host or vCenter Server URL paths may exploit this issue to steal cookies or redirect to malicious websites.
The vulnerability is classified under CWE-79, indicating it is a cross-site scripting issue. The CVSS score of 4.3 signifies that it poses a medium risk to organizations. This vulnerability was published on May 20, 2025. The attack vector is network-based, and it requires user interaction to exploit.
Technical Analysis
The root cause of this vulnerability stems from improper input validation within VMware ESXi and vCenter Server. Since the attack vector is network, attackers may exploit this vulnerability through crafted requests sent to the login page. The attack complexity is classified as low, meaning that attackers do not need advanced skills to exploit it.
No privileges are required to exploit this vulnerability, as it can be accessed by any user with network access. User interaction is required, as the victim must access a malicious link to be exploited. The confidentiality impact is assessed as low, while integrity and availability impacts are noted as none.
Risk & Impact Analysis
The real-world deployment risk associated with this vulnerability is significant, especially for organizations that utilize VMware ESXi and vCenter Server in their environments. Attackers can leverage this vulnerability to gain unauthorized access to session cookies, enabling them to impersonate legitimate users and potentially gain access to sensitive data.
Organizations should evaluate the potential blast radius of this vulnerability, as it could lead to widespread impacts across their digital infrastructure. The urgency assessment is categorized as medium due to the existing exploit availability, emphasizing the need for prompt remediation.
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions of VMware ESXi and vCenter Server prior to the vendor patch are affected by this vulnerability.
Mitigation & Remediation
Organizations should prioritize patching immediately. VMware has issued a patch that addresses this vulnerability. Upgrade to the latest version of VMware ESXi and vCenter Server to mitigate this risk.
If a patch is not available, organizations can implement configuration hardening measures to restrict access to the login pages of ESXi hosts and vCenter Servers to trusted networks only. Additionally, monitoring logs for unusual access patterns can help identify potential exploitation attempts.
For further guidance on securing your systems, organizations should consider engaging in penetration testing practices.
Detection Guidance
Organizations should monitor logs for potential indicators of exploitation, such as unexpected redirects or unauthorized attempts to access the login pages. Behavioral anomalies in user sessions may also indicate attempts to exploit this vulnerability.
AppSecure Threat Intelligence Insight
This vulnerability highlights the ongoing challenges of web application security and the necessity for effective input validation mechanisms. Organizations should remain vigilant in their security posture and consider implementing comprehensive security assessments to identify and remediate vulnerabilities proactively.
For insights on vulnerability management, organizations can refer to our blog on vulnerability management programs, and to understand the significance of penetration testing, they can explore our penetration testing methodology guide.
Organizations should also consider the implications of new vulnerabilities, such as those highlighted in our recent article on 2025 vulnerability exposure trends, to better prepare for future threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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