In WinRAR versions prior to and including 5.61, there is path traversal vulnerability when crafting the filename field of the ACE format. The UNACE module (UNACEV2.dll) creates files and folders as written in the filename field even when WinRAR validator noticed the traversal attempt and requestd to abort the extraction process. the operation is cancelled only after the folders and files were created but prior to them being written, therefore allowing the attacker to create empty files and folders everywhere in the file system.
Use CWE-693, Rarlab vendor hub and Winrar product page to widen CVE-2018-20251 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2025-8088, CVE-2025-6218 and CVE-2023-38831 for nearby disclosures in the same product family.