CVE-2025-53817 is a medium-severity vulnerability identified in the ipavlov variant of the 7-Zip file archiver, specifically affecting versions prior to 25.0.0. The vulnerability is classified as CWE-476, which corresponds to a NULL Pointer Dereference. This issue occurs within the Compound Document handler component of 7-Zip, a widely used open-source file compression and decompression tool known for its high compression ratio and support for multiple archive formats. The flaw arises when the software attempts to process certain Compound Documents and encounters a null pointer, leading to an unhandled exception that causes the application to crash. This results in a denial of service (DoS) condition, where the affected 7-Zip process terminates unexpectedly, potentially disrupting automated workflows or user operations that rely on file extraction. The vulnerability does not require user interaction, authentication, or elevated privileges to be exploited, but it does require local access to the system since the attack vector is local (AV:L). The CVSS 4.0 base score of 5.5 reflects a medium impact primarily due to the limited scope of the denial of service and the requirement for local access. No known exploits are currently reported in the wild, and the issue has been addressed in version 25.0.0 of 7-Zip. The fix involves proper validation and handling of pointers within the Compound Document handler to prevent dereferencing null pointers.

For European organizations, the impact of CVE-2025-53817 is primarily related to availability disruptions. Organizations that rely on 7-Zip for automated file extraction, archival processing, or integration into larger data processing pipelines may experience service interruptions if an attacker or malformed file triggers the null pointer dereference. This could affect sectors such as finance, healthcare, government, and manufacturing, where file archiving and extraction are routine operations. Although the vulnerability does not lead to code execution or data leakage, denial of service conditions can cause operational delays, loss of productivity, and potential cascading failures in dependent systems. Given that 7-Zip is widely used across Europe on both personal and enterprise endpoints, the risk is non-negligible. However, the requirement for local access limits remote exploitation, reducing the threat surface from external attackers. The absence of known exploits in the wild further lowers immediate risk but does not preclude future exploitation attempts.

European organizations should prioritize upgrading all instances of 7-Zip to version 25.0.0 or later, where the null pointer dereference vulnerability has been fixed. For environments where immediate patching is not feasible, implementing strict file validation and sandboxing of file extraction processes can reduce the risk of denial of service. Monitoring and logging of 7-Zip crashes should be enabled to detect potential exploitation attempts. Additionally, restricting local user permissions to prevent unauthorized execution of 7-Zip or limiting the ability to process untrusted Compound Documents can mitigate risk. Organizations should also educate users about the risks of opening files from untrusted sources and consider deploying endpoint protection solutions that can detect abnormal application crashes or suspicious file activities. Regular vulnerability scanning and asset inventory to identify outdated 7-Zip versions will support proactive risk management.