Overview
CVE-2025-64656 is a critical security vulnerability affecting Application Gateway. This vulnerability is an out-of-bounds read which, if exploited, allows an unauthorized attacker to elevate privileges within the network where the vulnerable Application Gateway is deployed. Given the potential for significant impact, prompt action is required to mitigate this risk.
Technical Details
The vulnerability stems from insufficient bounds checking when processing specific types of network traffic within the Application Gateway. An attacker can craft a malicious packet that, when processed by the gateway, causes it to read memory beyond the allocated buffer. This out-of-bounds read can leak sensitive information, potentially revealing credentials or internal system details. More importantly, it provides an avenue for privilege escalation by manipulating data structures in memory.
The exact vector and input required to trigger this vulnerability are not publicly disclosed to prevent widespread exploitation before patching. However, security researchers believe it relates to malformed HTTP headers or specific protocol extensions used by the Application Gateway.
CVSS Analysis
This vulnerability has been assigned a CVSS score of 9.4 (Critical), highlighting its severity.
- CVSS Base Score: 9.4
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- Scope: Changed
- Confidentiality Impact: High
- Integrity Impact: High
- Availability Impact: High
The high score is due to the ease of exploitation, lack of required privileges or user interaction, and the potential for complete system compromise.
Possible Impact
Successful exploitation of CVE-2025-64656 can lead to the following:
- Privilege Escalation: An attacker can gain administrative privileges on the Application Gateway and potentially other systems within the network.
- Data Breach: Sensitive data processed by the Application Gateway can be exposed.
- Denial of Service: The Application Gateway can be crashed, disrupting network services.
- Lateral Movement: Attackers can use the compromised gateway to move laterally within the network, compromising other systems and data.
Mitigation or Patch Steps
The primary mitigation step is to apply the security update provided by the vendor as soon as possible. Please follow these steps:
- Identify Affected Systems: Determine which Application Gateway instances are vulnerable.
- Apply the Patch: Download and install the patch from the vendor’s security portal. In this case, refer to the Microsoft Security Response Center (MSRC).
- Verify the Patch: After installation, verify that the patch has been applied correctly by checking the system logs and version information.
- Monitor for Suspicious Activity: Continuously monitor your network and Application Gateway logs for any signs of exploitation.
- Implement Workarounds (If Patching Is Delayed): If immediate patching is not possible, consider implementing temporary workarounds such as restricting access to the Application Gateway or using a Web Application Firewall (WAF) to filter potentially malicious traffic. Note: These are temporary measures and should not replace patching.
References
- Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-64656
