CVE-2020-25850 in MailSherlock
Summary
by MITRE • 12/31/2020
The function, view the source code, of HGiga MailSherlock does not validate specific characters. Remote attackers can use this flaw to download arbitrary system files.
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Analysis
by VulDB Data Team • 06/23/2026
The vulnerability in HGiga MailSherlock's view source code functionality represents a critical path traversal flaw that allows remote attackers to access arbitrary system files through improper input validation. This weakness stems from the application's failure to sanitize user-supplied parameters before processing them within the file viewing mechanism, creating an exploitable condition where malicious actors can manipulate the application's behavior to retrieve sensitive data from the underlying operating system.
This vulnerability aligns with CWE-22 Path Traversal and falls under the broader category of insecure direct object references as outlined in the OWASP Top Ten 2017. The flaw enables attackers to bypass normal access controls by crafting malicious input that includes directory traversal sequences such as ../ or ..\, allowing them to navigate the file system beyond intended boundaries. The absence of proper character validation and input sanitization creates a direct pathway for unauthorized file access, potentially exposing configuration files, source code, database credentials, and other sensitive system information.
The operational impact of this vulnerability extends beyond simple data theft, as it can enable attackers to gain insights into the application's architecture and underlying infrastructure. Remote exploitation allows adversaries to systematically enumerate system resources, potentially leading to privilege escalation opportunities or the discovery of additional vulnerabilities within the same environment. The attack surface expands significantly when considering that this flaw affects a core functionality of the mail application, making it a prime target for reconnaissance activities.
Mitigation strategies should focus on implementing robust input validation and sanitization mechanisms, including the use of allowlists for permitted characters and absolute path resolution techniques to prevent directory traversal attacks. Organizations should also implement proper access controls and least privilege principles to limit the damage potential even if such vulnerabilities are exploited. The remediation process must include thorough code review practices to identify similar patterns across the application codebase and implementation of web application firewalls that can detect and block suspicious file path sequences. Additionally, regular security testing including penetration testing and automated vulnerability scanning should be conducted to ensure comprehensive protection against similar flaws in other components of the system architecture.
The flaw demonstrates the critical importance of input validation in web applications and highlights how seemingly simple functionality can become a gateway for more sophisticated attacks when proper security controls are absent. This vulnerability serves as a reminder that all user-controllable inputs must be rigorously validated and sanitized to prevent attackers from manipulating application behavior in unintended ways, particularly in enterprise email systems where the potential impact of data exposure can be severe.