CVE-2014-7169 in Bash
Summary
by MITRE
GNU Bash through 4.3 bash43-025 processes trailing strings after certain malformed function definitions in the values of environment variables, which allows remote attackers to write to files or possibly have unknown other impact via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-6271.
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Analysis
by VulDB Data Team • 04/22/2026
The vulnerability identified as CVE-2014-7169 represents a critical security flaw in GNU Bash that emerged from an incomplete remediation of the previously discovered CVE-2014-6271 vulnerability. This issue specifically affects Bash versions through 4.3 bash43-025 and stems from the shell's improper handling of environment variables containing malformed function definitions. The flaw occurs when Bash processes trailing strings that follow certain malformed function definitions within environment variable values, creating a persistent security risk that extends beyond simple command execution. This vulnerability operates at the core of Unix-like system security mechanisms where environment variables are routinely passed between processes across privilege boundaries, making it particularly dangerous in server environments and network services that utilize shell execution.
The technical implementation of this vulnerability involves the exploitation of Bash's environment variable parsing mechanism through crafted malicious input that appears in environment variables. When Bash encounters a malformed function definition within an environment variable value, it continues processing any trailing content that follows the function definition, effectively allowing arbitrary code execution. This behavior manifests in various attack vectors including the ForceCommand feature in OpenSSH sshd where malicious environment variables can be injected during SSH connections, Apache HTTP Server modules mod_cgi and mod_cgid where CGI scripts execute with potentially compromised environment variables, and DHCP clients that may execute shell commands with environment variables set by network infrastructure. The vulnerability specifically leverages the incomplete patch for CVE-2014-6271, which failed to address all possible attack vectors, leaving a persistent backdoor for remote code execution.
The operational impact of CVE-2014-7169 extends far beyond traditional command injection scenarios, creating widespread potential for system compromise across multiple network services and protocols. Attackers can leverage this vulnerability to write to arbitrary files on the target system, execute unauthorized commands with elevated privileges, and potentially establish persistent backdoors in compromised environments. The vulnerability's reach is amplified by its presence in common system components such as SSH daemons, web server CGI handlers, and network protocol implementations where environment variables are routinely passed across security boundaries. This allows attackers to exploit the vulnerability in scenarios ranging from simple SSH connections to complex multi-hop attacks through compromised network infrastructure, making it particularly dangerous for enterprise environments where these services are prevalent. The vulnerability's persistence in systems that have patched CVE-2014-6271 demonstrates how incomplete security fixes can create long-term exposure risks that may remain undetected for extended periods.
Mitigation strategies for CVE-2014-7169 require immediate patching of affected Bash versions to the corrected releases that properly address all attack vectors related to malformed function definitions in environment variables. Organizations should prioritize updating their systems to Bash versions 4.3 patch 25 or later, which contain the complete fix for both CVE-2014-6271 and CVE-2014-7169. Additional protective measures include implementing strict environment variable validation in network services, configuring proper input sanitization for all environment variables that traverse privilege boundaries, and monitoring for suspicious environment variable content in system logs. Security professionals should also consider implementing network-based intrusion detection systems to detect exploitation attempts, particularly focusing on environment variable content that may contain malformed function definitions. The vulnerability's classification under CWE-78 and its alignment with ATT&CK techniques related to command and control operations and privilege escalation highlight the need for comprehensive security monitoring and incident response procedures. System administrators should also review and audit all services that may be vulnerable to this attack vector, particularly those that execute shell commands or process environment variables from untrusted sources, ensuring that proper security controls are in place to prevent exploitation attempts.