CVE-2026-50426 in Windows
Summary
by MITRE • 07/14/2026
Relative path traversal in DNS Server allows an authorized attacker to execute code over an adjacent network.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 07/14/2026
This vulnerability represents a critical security flaw in DNS server implementations that enables unauthorized code execution through relative path traversal techniques. The issue arises when DNS servers fail to properly validate or sanitize file paths during processing of DNS requests, allowing attackers to manipulate directory traversal sequences that can lead to arbitrary code execution. Such vulnerabilities typically occur in environments where DNS servers handle configuration files, zone data, or other resources that require path resolution. The attack vector specifically targets adjacent network environments where the attacker has access to the local network but not direct administrative privileges, making this a particularly concerning threat as it can be exploited without requiring extensive reconnaissance or bypassing traditional network security controls.
The technical implementation of this vulnerability stems from improper input validation within DNS server components that process relative path references. When DNS servers receive requests containing malformed or specially crafted path sequences, they may interpret these inputs as legitimate file system operations rather than malicious attempts to traverse directories. This flaw commonly manifests in scenarios where DNS servers maintain configuration files in hierarchical directory structures, or when they process zone transfer data that includes relative path references. The vulnerability operates at the application layer and can be classified under CWE-22 - Improper Limitation of a Pathname to a Restricted Directory, which is a well-documented weakness in software security that specifically addresses path traversal attacks. The attack leverages the fundamental trust placed in DNS server operations and exploits the assumption that incoming requests contain legitimate path references rather than maliciously crafted sequences.
The operational impact of this vulnerability extends beyond simple code execution capabilities as it provides attackers with persistent access to network infrastructure that can serve as a launching point for further attacks within the organization. Once an attacker successfully executes code through this vulnerability, they can potentially establish backdoors, escalate privileges, or use the compromised DNS server to launch additional attacks against internal systems. This threat is particularly dangerous in enterprise environments where DNS servers often maintain critical network infrastructure information and serve as authoritative sources for domain resolution. The adjacent network requirement means that attackers must be physically or logically close to the target environment, which can include scenarios such as disgruntled employees, contractors with local access, or compromised devices on the same network segment. This restriction actually makes the vulnerability more likely to succeed in targeted attacks rather than broad scanning campaigns, as it requires attackers to already have some level of network presence.
Effective mitigation strategies for this vulnerability require a multi-layered approach that addresses both the immediate technical flaw and broader security posture issues. Organizations should implement strict input validation mechanisms within DNS server implementations to prevent any relative path traversal sequences from being processed as legitimate file system operations. This includes deploying proper path sanitization routines that strip or reject directory traversal characters, implementing robust access controls for DNS server components, and ensuring that DNS servers operate with minimal required privileges. Network segmentation and firewall rules should be configured to limit unnecessary communication between DNS servers and other network segments, reducing the attack surface for adjacent network exploitation attempts. Additionally, regular security assessments should be conducted to identify similar vulnerabilities in other network services that may present similar path traversal risks, as these issues often occur in systems that handle file system operations. The remediation process should align with established security frameworks such as the mitre ATT&CK framework's techniques for privilege escalation and lateral movement, as this vulnerability can serve as a foothold for more extensive compromise operations within target networks.