CVE-2009-1299 in PulseAudio
Summary
by MITRE
The pa_make_secure_dir function in core-util.c in PulseAudio 0.9.10 and 0.9.19 allows local users to change the ownership and permissions of arbitrary files via a symlink attack on a /tmp/.esd-##### temporary file.
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Analysis
by VulDB Data Team • 05/02/2026
The vulnerability described in CVE-2009-1299 represents a critical security flaw in PulseAudio's file handling mechanisms that enables local privilege escalation through a carefully crafted symlink attack. This issue affects PulseAudio versions 0.9.10 and 0.9.19, where the pa_make_secure_dir function in core-util.c demonstrates a dangerous lack of proper file validation during temporary file creation. The flaw arises from the application's failure to adequately verify the security of temporary file paths before attempting to establish ownership and permissions, creating an avenue for malicious users to manipulate the system's file permissions.
The technical implementation of this vulnerability stems from the insecure handling of temporary files in the /tmp directory space, specifically targeting the /tmp/.esd-##### naming convention used by PulseAudio. When the pa_make_secure_dir function processes temporary file creation, it does not properly validate whether the target path is a symbolic link or if it points to an existing file that could be manipulated by an attacker. This insecure direct object reference pattern allows a local attacker to create a malicious symbolic link that points to a target file of their choice, effectively enabling them to modify the ownership and permissions of arbitrary system files.
The operational impact of this vulnerability extends beyond simple file permission manipulation, as it provides attackers with a mechanism to escalate privileges and potentially compromise the entire system. By exploiting this flaw, an attacker can gain unauthorized access to critical system files, modify system configurations, or even establish persistent access mechanisms within the affected system. The vulnerability is particularly dangerous because it operates at the local user level, meaning that any user with access to the system can potentially exploit it without requiring special privileges or network access. This makes it a significant concern for multi-user systems where different users may have varying levels of access and security requirements.
From a cybersecurity perspective, this vulnerability aligns with CWE-377, which addresses insecure temporary file handling, and represents a classic example of a race condition vulnerability that can be exploited through symlink attacks. The attack vector follows the patterns described in the MITRE ATT&CK framework under T1068, which covers the exploitation of remote services or local processes to gain unauthorized access. The flaw demonstrates poor secure coding practices where the application assumes that temporary file operations will proceed safely without proper validation of the file system state. Organizations affected by this vulnerability should immediately implement mitigations including updating to patched versions of PulseAudio, implementing proper file system permissions, and conducting security reviews of temporary file handling code to prevent similar issues from occurring in other applications. The vulnerability also highlights the importance of proper privilege separation and secure temporary file creation practices as outlined in various security standards and best practices for system hardening.