A critical path traversal zero-day vulnerability — tracked as CVE‑2025‑8088 — has been identified in WinRAR and related components (Windows RAR, UnRAR.dll, and the portable UnRAR source code), and is currently being actively exploited. Review the details in this Cybersecurity Threat Advisory to understand the risks and learn how to mitigate them effectively.
What is the threat?
This vulnerability allows malicious file to escape the folder they are supposed to stay in and place themselves in unauthorized locations on computers. Security analysts discovered this issue in WinRAR, a tool used for opening compressed files such as .zip or .rar archives.
To exploit this vulnerability, an attacker creates a malicious archive file. When someone opens it with WinRAR, it silently drops malware into a special folder on the system. This malware is designed to automatically execute on system startup — meaning even if you don’t click anything or notice anything unusual, the malware is already set to launch the next time you reboot..
This kind of automatic execution is dangerous because it gives attackers a persistent foothold on your system. From there, they can eavesdrop on activity, steal data, or spread further across your network.
Why is it noteworthy?
This vulnerability is especially concerning because it’s being actively exploited in real-world attacks targeting organizations across critical industries. Notably, another high-severity flaw in WinRAR (CVE-2025-6218) was patched just two months ago. The close timing of these vulnerabilities highlights how frequently attackers are targeting WinRAR, emphasizing the need to properly secure and manage the software. What makes this threat even more dangerous is that WinRAR does not update automatically. The lack of automatic updates means many users may still be running outdated and vulnerable versions without realizing it. As a result, a single user extracting a malicious archive could unknowingly compromise their entire system.
Tools like WinRAR can fall under the category of Shadow IT, software used by employees that isn’t officially managed or monitored by an organization’s IT department. These kinds of tools often fly under the radar, making them a perfect entry point for attackers. If no one knows they’re being used, no one’s ensuring they’re secure or up to date.
What is the exposure or risk?
This high-risk vulnerability allows attackers to exploit systems without administrator privileges, making even standard user accounts vulnerable. Once malware is placed into the startup folder, it runs automatically on reboot, giving attackers persistent access without further interaction. If exploited on a device with elevated permissions, attackers could disable security tools, spread laterally, or compromise entire organizations.
BYOD (Bring Your Own Device) and remote work environments are particularly vulnerable, as these devices often fall outside of regular patch management and may run outdated or unapproved software. The presence of Shadow IT, lack of software visibility, and user behavior (e.g., opening untrusted archives via phishing emails) all increase the likelihood of successful exploitation. In organizations without strict access controls, such as least privilege enforcement, this vulnerability can lead to widespread damage from a single compromised endpoint.
What are the recommendations?
Barracuda recommends the following actions to protect your endpoints:
- Update WinRAR immediately to version 7.13, which contains the patch for this vulnerability.
- Implement centralized patch management to consistently update all systems across the organization.
- Educate users to avoid opening unsolicited or suspicious RAR files, even if they appear to be documents or job applications.
- Use endpoint protection and EDR tools, such as Barracuda Managed XDR Endpoint Security, to detect and block suspicious behaviors associated with archive extraction and unauthorized file placement.
- Monitor startup directories and system logs for signs of tampering or unknown executable files.
- Restrict the use of third-party archive tools in sensitive environments if they do not support automated updates or verification.
References
For more in-depth information about the recommendations, please visit the following links:
- https://www.helpnetsecurity.com/2025/08/11/winrar-zero-day-cve-2025-8088/
- https://thehackernews.com/2025/08/winrar-zero-day-under-active.html
- https://cybersecuritynews.com/winrar-0-day-in-phishing-attacks/
- https://hackread.com/winrar-zero-day-cve-2025-8088-spread-romcom-malware/
If you have any questions about this Cybersecurity Threat Advisory, don’t hesitate to get in touch with Barracuda Managed XDR’s Security Operations Center.
