CVE-2010-1129 in PHP
Summary
by MITRE
The safe_mode implementation in PHP before 5.2.13 does not properly handle directory pathnames that lack a trailing / (slash) character, which allows context-dependent attackers to bypass intended access restrictions via vectors related to use of the tempnam function.
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Analysis
by VulDB Data Team • 05/03/2026
The vulnerability identified as CVE-2010-1129 represents a critical security flaw in PHP's safe_mode implementation that existed prior to version 5.2.13. This issue stems from improper handling of directory pathnames within the PHP runtime environment, specifically when these paths lack a trailing forward slash character. The safe_mode feature was designed to provide an additional layer of security by restricting file operations and directory access based on the user context, but this implementation flaw created a significant bypass mechanism that attackers could exploit to circumvent intended access controls.
The technical root cause of this vulnerability lies in how PHP's safe_mode mechanism processes directory pathnames during file operations, particularly when the tempnam function is invoked. When a directory path is specified without a trailing slash, the safe_mode implementation fails to properly validate whether the specified path constitutes a valid directory or if it might be interpreted as a file path. This inconsistency in path validation creates a scenario where an attacker can manipulate directory references to access files or directories that should otherwise be restricted. The vulnerability is context-dependent because it requires specific conditions to be met, including the presence of a directory path without a trailing slash and the use of the tempnam function which is commonly employed in PHP applications for temporary file creation.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally undermines the security model that safe_mode was intended to enforce. Attackers can leverage this flaw to bypass access restrictions and potentially gain unauthorized access to sensitive files, execute arbitrary code, or perform other malicious activities within the application's execution context. This vulnerability is particularly concerning because it affects applications that rely on PHP's safe_mode for security enforcement, potentially allowing attackers to access files that should be protected by the safe_mode restrictions. The exploitation of this vulnerability demonstrates a failure in proper input validation and path handling that violates fundamental security principles.
Security practitioners should consider this vulnerability in relation to CWE-22, which addresses improper limitation of a pathname to a restricted directory, and CWE-252, which covers improper restriction of operations within a security context. The attack pattern aligns with techniques described in the MITRE ATT&CK framework under the T1059 category for command and scripting interpreter, as attackers may use this vulnerability to execute malicious code through compromised PHP applications. Mitigation strategies should include immediate patching of affected PHP installations to version 5.2.13 or later, implementation of proper directory path validation in application code, and consideration of alternative security models since safe_mode has been deprecated in modern PHP versions. Organizations should also review their PHP application configurations and ensure that directory permissions are properly enforced through additional security layers beyond the deprecated safe_mode functionality.