Winrar
CVE-2018-20250
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V14 - Configuration Dependency management, component inventory
|
| Impact | High risk (EPSS 93.5%). WinRAR has over 500 million users. The 19-year-old UNACEV2.dll had never been updated (source code was lost). The Startup folder attack vector enables persistent malware installation with a single archive extraction. |
| Exploit ScenarioDerived | A user downloads or receives a crafted RAR archive (actually ACE format). Extracting it with WinRAR appears to extract normal files to the chosen directory, but secretly also writes a malicious .exe to C:\Users\<user>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup\, which executes automatically on next login. |
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Alert meAnalysisAIv1 – Mar 26, 2026
WinRAR before 5.61 contains a path traversal vulnerability in the ACE archive format handler (UNACEV2.dll) that allows extraction of files to arbitrary locations, enabling persistent malware installation through Startup folder placement.
Earlier versions of this analysis (1)
A path traversal vulnerability in WinRAR's ACE archive handling DLL (UNACEV2.dll) allows crafted archives to extract files to arbitrary filesystem locations, bypassing the intended extraction directory.
RemediationAI
Update WinRAR to 5.70+ which removed ACE format support entirely (UNACEV2.dll deleted). The DLL cannot be patched as source code was lost. Alternatively, manually delete UNACEV2.dll from WinRAR installation directory.
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Technical ContextAI · show details
The CWE-36 path traversal in UNACEV2.dll occurs when parsing the filename field of ACE format archives. By manipulating the filename with traversal sequences, attackers can write files to any writable location. The classic attack writes a malicious executable to the Windows Startup folder for persistence.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
Lifecycle Timeline
3DescriptionNVD
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.
Executive ViewAI
Organizations using WinRAR face notable risk from CVE-2018-20250 rated CVSS 7.8. Exploitation could compromise the security of affected deployments. This vulnerability is actively exploited in the wild (KEV-listed) and requires immediate remediation. Immediate patching is required per CISA KEV mandate.
Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.
Threat Intelligence Overview
NVD
CVE.org
CISA KEV
EPSS
Exploit-DB
GitHub
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Path traversal exploits occur when applications use user-controlled input to construct file system paths without proper validation.
Affected Products (CPE)NVD
RARLAB WinRAR before 6.23 allows attackers to execute arbitrary code when a user attempts to view a benign file within a
WinRAR for Windows contains a path traversal vulnerability allowing crafted archives to execute arbitrary code, discover
WinRAR contains a directory traversal vulnerability (CVE-2025-6218, CVSS 7.8) enabling remote code execution when users
RARLAB WinRAR before 7.00, on Windows, allows attackers to spoof the screen output via ANSI escape sequences, a differen
RARLAB WinRAR before 7.00, on Linux and UNIX platforms, allows attackers to spoof the screen output, or cause a denial o
WinRAR 5.61 contains a denial of service vulnerability that allows local attackers to crash the application by placing a
Out-of-bounds heap write in the RAR5 recovery-volume (.rev) parser of WinRAR, RAR, UnRAR, and unrar.dll (versions before
The file-execution functionality in WinRAR before 5.30 beta 5 allows local users to gain privileges via a Trojan horse f
Issue that bypasses the "Mark of the Web" security warning function for files when opening a symbolic link that points t
RARLAB WinRAR Mark-Of-The-Web Bypass Vulnerability. Rated medium severity (CVSS 4.3), this vulnerability is remotely exp
Cross-site scripting (XSS) vulnerability in the generate report functionality in Rarlab WinRAR 7.11, allows attackers to