CVE-2018-20250: WinRAR Absolute Path Traversal Vulnerability

Vulnerability summary

CVE-2018-20250 is a high (CVSS 7.8) Absolute Path Traversal vulnerability in RARLAB WinRAR. It is known to be exploited: CISA lists it, first on 15-02-2022. It has been used in ransomware campaigns. EPSS estimates a 96.00% chance of exploitation in the next 30 days, higher than 99.8% of scored vulnerabilities. 6 public exploits are recorded.

Timeline

1. 05-02-2019
   PublishedVulnerability first disclosed.
2. 15-02-2022
   Added to CISA KEVWinRAR Absolute Path Traversal Vulnerability
3. 15-08-2022
   CISA remediation dueApply updates per vendor instructions.
4. 13-08-2026
   Last modifiedVulnerability information updated.

Description

In WinRAR versions prior to and including 5.61, There is path traversal vulnerability when crafting the filename field of the ACE format (in UNACEV2.dll). When the filename field is manipulated with specific patterns, the destination (extraction) folder is ignored, thus treating the filename as an absolute path.

• CWE-36Absolute Path TraversalThe product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize absolute path sequences such as "/abs/path" that can resolve to a location that is outside of that directory.
• CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.