CVE-2026-65794 in Windows
Summary
by MITRE • 08/12/2026
Buffer over-read in Windows SMB Client allows an unauthorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical buffer over-read condition within the Windows Server Message Block client implementation that enables remote information disclosure attacks. The flaw occurs when the smbclient component processes specially crafted network requests, causing it to read memory beyond the allocated buffer boundaries. This type of vulnerability falls under the common weakness enumeration CWE-125 which specifically addresses out-of-bounds read conditions in software implementations. The security impact is significant as attackers can leverage this issue to extract sensitive data from memory locations that should remain protected, potentially including credentials, session tokens, or other confidential information.
The technical execution of this vulnerability requires an attacker to establish communication with a target system running the affected Windows SMB client functionality. When legitimate network traffic containing malformed SMB packets is processed by the vulnerable component, the buffer over-read occurs during parsing operations. This condition typically manifests when the client receives responses from SMB servers that contain oversized or improperly formatted data structures. The ATT&CK framework categorizes this as a technique involving information gathering through network protocols, specifically leveraging protocol implementation weaknesses to extract valuable data elements from system memory.
Operational impact of this vulnerability extends beyond simple information disclosure, as the extracted data could potentially enable more sophisticated attacks including credential harvesting, session hijacking, or further exploitation attempts. The remote nature of this vulnerability means that attackers do not require local system access or physical presence to exploit it, making it particularly dangerous in enterprise environments where SMB traffic flows between multiple systems. Organizations with extensive network infrastructure using SMB protocols for file sharing, printer services, or other network functions face elevated risk exposure, as the attack surface includes numerous potential entry points through which this vulnerability can be exploited.
Mitigation strategies should prioritize immediate patch application from Microsoft security updates targeting the specific SMB client implementation flaws. Network segmentation and firewall rules can help limit exposure by restricting SMB traffic between systems where possible. Implementing monitoring solutions that detect anomalous SMB packet patterns or unusual memory access behaviors provides additional defense layers against exploitation attempts. Security teams should also consider disabling unnecessary SMB server functionality on systems that do not require it, reducing the attack surface while maintaining essential operational requirements. The vulnerability highlights the importance of regular security assessments and proactive patch management programs to address similar implementation weaknesses before they can be exploited by malicious actors in the wild.