CVE-2025-9809 in libretro-common
Summary
by MITRE • 09/01/2025
Out-of-bounds write in cdfs_open_cue_track in libretro libretro-common latest on all platforms allows remote attackers to execute arbitrary code via a crafted .cue file with a file path exceeding PATH_MAX_LENGTH that is copied using memcpy into a fixed-size buffer.
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Analysis
by VulDB Data Team • 12/08/2025
The vulnerability identified as CVE-2025-9809 represents a critical out-of-bounds write condition within the cdfs_open_cue_track function of libretro-common library, a widely used component in retro gaming emulators and multimedia applications. This flaw exists in the handling of CD image cue files, which are commonly used to define audio tracks and data segments for optical disc images. The vulnerability manifests when a remote attacker crafts a malicious .cue file containing a file path that exceeds the PATH_MAX_LENGTH constant, enabling arbitrary code execution through a dangerous memory copy operation.
The technical root cause of this vulnerability lies in the improper bounds checking during the processing of file paths within the cue file parsing logic. When the system encounters a crafted .cue file with an excessively long path, the memcpy function is invoked to copy this path into a fixed-size buffer without adequate validation of the source length against the destination buffer capacity. This classic buffer overflow scenario occurs because the implementation fails to account for the maximum allowable path length, directly violating fundamental memory safety principles. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which is particularly dangerous due to its potential for arbitrary code execution through stack corruption.
The operational impact of this vulnerability extends across all platforms where libretro-common is deployed, including desktop operating systems, mobile platforms, and embedded systems running retro gaming emulators. Attackers can exploit this weakness by hosting malicious .cue files on remote servers or embedding them in compromised software packages. When a vulnerable application processes these crafted files, the out-of-bounds write corrupts adjacent memory locations, potentially overwriting function pointers, return addresses, or other critical program data structures. This memory corruption can lead to privilege escalation, denial of service, or complete system compromise depending on the execution environment and target application privileges.
The attack surface for this vulnerability is particularly broad given the widespread adoption of libretro-common in various multimedia applications and emulator frameworks. Systems that process CD image files, including retro gaming emulators, media players, and digital asset management tools, are all potentially at risk. The remote exploitation capability makes this vulnerability especially concerning as attackers can deliver malicious payloads through web-based channels without requiring local access to the target system. This aligns with ATT&CK technique T1059.007 for command and control through application layer protocols, as the vulnerability enables remote code execution through legitimate application interfaces.
Mitigation strategies for CVE-2025-9809 should focus on immediate codebase updates and defensive programming practices. The primary solution involves implementing proper bounds checking before any memory copy operations, ensuring that source path lengths are validated against destination buffer sizes. Developers should replace unsafe memcpy calls with safer alternatives such as strlcpy or explicit length validation routines that prevent buffer overflows. Additionally, implementing stack canaries, address space layout randomization, and other exploit mitigation techniques can help reduce the effectiveness of potential exploitation attempts. The vulnerability highlights the importance of adhering to secure coding practices and following industry standards such as those outlined in the CERT C Secure Coding Standard, particularly guidelines related to buffer overflow prevention and memory safety. Organizations should prioritize patching affected applications and monitoring for exploitation attempts while implementing proper input validation mechanisms in all file path processing code.