CVE-2025-53817 identifies a null pointer dereference vulnerability (CWE-476) in the ipavlov 7-Zip file archiver prior to version 25.0.0. The flaw exists in the Compound Document handler component, which is responsible for extracting files from Compound Document formats. When processing a specially crafted archive, the handler may dereference a null pointer, causing the application to crash and resulting in a denial of service condition. This vulnerability does not require authentication or user interaction but does require local access to the vulnerable application to trigger. The CVSS v4.0 base score is 5.5 (medium), reflecting a locally exploitable DoS with no impact on confidentiality, integrity, or availability beyond the application crash. No known exploits have been reported in the wild, and the issue was fixed in 7-Zip version 25.0.0. The vulnerability primarily affects systems that use 7-Zip for extracting Compound Documents, which are common in office and enterprise environments. The flaw could be exploited by an attacker who can supply malicious archive files to a user or system running a vulnerable version, causing service interruptions or application crashes. The fix involves proper null pointer checks and error handling in the Compound handler code to prevent dereferencing null pointers.

For European organizations, the primary impact is denial of service through application crashes when processing maliciously crafted archive files. This can disrupt workflows, especially in environments where 7-Zip is used for automated or bulk extraction of Compound Documents, such as document management systems or email gateways. While the vulnerability does not allow code execution or data compromise, repeated exploitation could lead to operational downtime and potential loss of productivity. Organizations handling large volumes of untrusted archives or with automated extraction processes are at higher risk. The lack of user interaction requirement means that systems processing files automatically could be vulnerable to remote DoS if attackers can deliver crafted files. However, the local access vector limits remote exploitation unless combined with other attack vectors. No known active exploitation reduces immediate risk but patching remains critical to prevent future attacks.

The most effective mitigation is to upgrade all affected 7-Zip installations to version 25.0.0 or later, which contains the fix for this vulnerability. Organizations should audit their environments to identify systems running vulnerable versions and prioritize patching. Additionally, implement strict file handling policies that restrict or scan archive files from untrusted sources before extraction. Employ sandboxing or isolated environments for processing potentially malicious archives to contain crashes and prevent wider impact. Monitoring application logs for unexpected crashes related to 7-Zip can help detect attempted exploitation. For automated extraction systems, incorporate input validation and error handling to gracefully manage malformed archives. Educate users about the risks of opening untrusted archive files and encourage use of updated software. Finally, maintain an inventory of software versions and apply security updates promptly to reduce exposure.