CVE-2026-50695 in Windows
Summary
by MITRE • 07/14/2026
Stack-based buffer overflow in Active Directory Federation Services allows an unauthorized attacker to deny service over a network.
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Analysis
by VulDB Data Team • 07/14/2026
This vulnerability represents a critical stack-based buffer overflow within Active Directory Federation Services that enables remote attackers to execute denial of service attacks against targeted systems. The flaw occurs when the federation service processes malformed input data through its authentication handling mechanisms, specifically within the token validation and processing components. Attackers can exploit this weakness by sending specially crafted federation requests that exceed the allocated stack buffer space, causing unpredictable behavior including application crashes, memory corruption, or complete service unavailability. The vulnerability stems from inadequate input validation and bounds checking within the federated authentication flow where user credentials or security tokens are processed before being validated against the identity provider. This issue directly maps to CWE-121 Stack-based Buffer Overflow, which falls under the broader category of injection vulnerabilities that have been consistently identified as high-risk threats in cybersecurity frameworks. The attack vector operates over network protocols such as ws-trust and saml authentication exchanges, making it particularly dangerous in enterprise environments where federated identity services form the backbone of single sign-on operations. Organizations relying on AD FS for cross-domain authentication face severe operational disruption when this vulnerability is exploited, potentially affecting thousands of users across multiple applications and systems that depend on centralized identity management. The impact extends beyond simple service interruption as attackers can cause cascading failures throughout integrated systems, particularly in environments where federated services are critical for business continuity. This type of vulnerability aligns with ATT&CK technique T1499.004 Network Denial of Service, specifically targeting authentication infrastructure to disrupt legitimate user access and system operations. The exploitation requires minimal privileges and can be automated through readily available tools, making it particularly attractive to threat actors seeking to cause maximum disruption with minimal effort. Organizations should prioritize immediate patching of affected AD FS versions while implementing network segmentation controls that limit exposure to this vulnerability.
The technical implementation of this buffer overflow exploit involves carefully crafted malicious requests that force the service to write data beyond allocated memory boundaries in the stack frame. When legitimate authentication requests contain oversized parameters or malformed token structures, the processing code fails to properly validate input length before copying data into fixed-size buffers. This creates an opportunity for attackers to overwrite adjacent stack memory locations including return addresses and function pointers, potentially leading to arbitrary code execution or service termination. The vulnerability is particularly insidious because it affects the core authentication infrastructure that many enterprise applications depend upon, making it a prime target for sophisticated attack campaigns. Security researchers have identified that this flaw exists across multiple versions of AD FS where proper input sanitization mechanisms were either absent or insufficiently implemented, particularly in scenarios involving complex token processing workflows. The exploitation process typically involves sending malformed SAML assertions or ws-trust messages that trigger the vulnerable code path during security token validation. Network monitoring systems should be configured to detect unusual authentication request patterns and oversized data transfers that may indicate attempts to exploit this vulnerability. Organizations implementing compensating controls should consider deploying application firewalls and input validation rules specifically designed to block suspicious authentication requests before they reach the vulnerable service components.
Mitigation strategies for this vulnerability must address both immediate defensive measures and long-term architectural improvements to protect federated identity infrastructure. Microsoft has released security updates that correct the buffer overflow conditions through proper input length validation and enhanced memory management practices within AD FS components. Organizations should implement comprehensive patch management processes that prioritize timely deployment of security updates, particularly those addressing authentication service vulnerabilities. Network-level protections include configuring firewalls to limit access to federation endpoints, implementing rate limiting controls to prevent abuse of authentication services, and establishing monitoring rules for detecting anomalous authentication traffic patterns. The implementation of robust input validation frameworks within federated services helps prevent similar issues by ensuring all external data is properly sanitized before processing. Security teams should conduct regular vulnerability assessments targeting authentication infrastructure components to identify potential weaknesses that could be exploited in similar manners. Industry best practices recommend maintaining detailed audit logs of all authentication activities and establishing automated alerting systems for unusual service behavior that may indicate exploitation attempts. Organizations should also consider implementing redundant authentication mechanisms and backup services to ensure business continuity during potential exploitation events, particularly in mission-critical environments where federated identity services are essential for operations. The vulnerability demonstrates the importance of maintaining security hygiene in enterprise identity infrastructure, as even seemingly minor input validation issues can result in significant service disruption and operational impact across entire organizations relying on federated authentication systems.