Privilege escalation in WinRAR - CVE-2018-20251
Published: February 11, 2019 / Updated: May 18, 2020
Vulnerability identifier: #VU17469
CSH Severity: Low
CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2018-20251
CWE-ID: CWE-264
Exploitation vector: Local access
Exploit availability:
Public exploit is available
Vulnerability details
The vulnerability allows a local attacker to gain elevated privileges.
The vulnerability exists due to a validation function (in WinRAR code) that inspects the filename field for each compressed file in the ACE archive is being called before extraction of ACE archives. The extraction operation should be aborted and no file or folder should be extracted. However, the check of the return value from the validator function made too late (in UNACEV2.dll), after the creation of files and folders. A local attacker can disallow the filename by the validator function (for example, the filename contains path traversal patterns) and gain elevated privileges.
Affected software
WinRAR
How to mitigate CVE-2018-20251
Update to version 5.70 Beta 1.
WinRAR - update to 5.70 beta 1