CVE-2016-2087 in HexChat
Summary
by MITRE
Directory traversal vulnerability in the client in HexChat 2.11.0 allows remote IRC servers to read or modify arbitrary files via a .. (dot dot) in the server name.
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Analysis
by VulDB Data Team • 05/13/2026
The vulnerability identified as CVE-2016-2087 represents a critical directory traversal flaw within the client component of HexChat version 2.11.0. This security weakness specifically affects the handling of server names in the IRC client's network communication system, creating a pathway for remote attackers to manipulate file system access through maliciously crafted server identifiers. The vulnerability stems from insufficient input validation and sanitization of server name parameters, which are processed without proper security checks that would normally prevent path traversal sequences.
The technical exploitation of this vulnerability occurs when an attacker controls a remote IRC server that communicates with a vulnerable HexChat client. By crafting a server name that contains directory traversal sequences such as "..", the malicious server can manipulate the client's file operations to access or modify files outside of the intended directory scope. This flaw operates at the application layer and leverages the client's trust in server-provided information to execute unauthorized file system operations. The vulnerability is classified under CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks.
The operational impact of CVE-2016-2087 extends beyond simple file access violations to potentially enable full system compromise. An attacker could leverage this vulnerability to read sensitive configuration files, modify client-side scripts, access user credentials stored in plain text, or even execute arbitrary code if the client has sufficient privileges. The attack vector is particularly concerning because it requires minimal user interaction beyond connecting to a malicious IRC server, making it a significant risk in environments where users connect to untrusted IRC networks. This vulnerability directly aligns with ATT&CK technique T1190, which covers exploitation of remote services through network-based attacks, and T1059, which involves the execution of commands through the command and control channel.
Mitigation strategies for this vulnerability should focus on immediate patching of the HexChat client to version 2.12.0 or later, which contains the necessary fixes for proper input validation. Additionally, network administrators should implement strict access controls for IRC networks, monitor for suspicious server names, and educate users about the risks of connecting to untrusted IRC servers. The fix typically involves implementing proper input sanitization routines that strip or escape directory traversal sequences from server names before any file system operations are performed. Organizations should also consider network segmentation and firewall rules to limit IRC client access to trusted networks, reducing the attack surface and potential impact of such vulnerabilities in the broader security infrastructure.