CVE-2025-32820: SonicWall SMA 100 Path Traversal Flaw

CVE-2025-32820 Overview

A path traversal vulnerability exists in SonicWall SMA100 series appliances that allows a remote authenticated attacker with SSLVPN user privileges to inject a path traversal sequence to make any directory on the SMA appliance writable. This vulnerability, classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), enables attackers to bypass directory access controls and potentially compromise the integrity of critical system files.

Critical Impact

Authenticated attackers can modify arbitrary directories on vulnerable SonicWall SMA appliances, potentially leading to system compromise, configuration tampering, or persistent access mechanisms.

Affected Products

• SonicWall SMA 100 Firmware
• SonicWall SMA 200 / SMA 200 Firmware
• SonicWall SMA 210 / SMA 210 Firmware
• SonicWall SMA 400 / SMA 400 Firmware
• SonicWall SMA 410 / SMA 410 Firmware
• SonicWall SMA 500v / SMA 500v Firmware

Discovery Timeline

• May 7, 2025 - CVE-2025-32820 published to NVD
• May 19, 2025 - Last updated in NVD database

Technical Details for CVE-2025-32820

Vulnerability Analysis

This path traversal vulnerability affects the SonicWall Secure Mobile Access (SMA) 100 series appliances. The flaw allows authenticated users with standard SSLVPN privileges to craft malicious requests containing directory traversal sequences (such as ../) that bypass intended path restrictions. Once exploited, the attacker gains write permissions to arbitrary directories on the appliance filesystem.

The vulnerability is particularly concerning because it requires only low-privilege SSLVPN credentials—the type commonly provisioned to remote workers—to exploit. Since SMA appliances serve as network perimeter devices providing remote access, successful exploitation could allow attackers to modify system configurations, plant backdoors, or tamper with authentication mechanisms.

Root Cause

The vulnerability stems from improper input validation in the SMA100 firmware's handling of file path parameters. The application fails to adequately sanitize user-supplied input for directory traversal sequences before using it in file system operations. This allows attackers to escape the intended directory scope and gain write access to directories outside the expected path hierarchy.

Attack Vector

The attack is network-based and can be executed remotely by any authenticated SSLVPN user. The attacker does not require administrative privileges—standard user credentials are sufficient. The exploitation flow involves:

1. Authenticating to the SMA appliance using valid SSLVPN credentials
2. Crafting a malicious request containing path traversal sequences (e.g., ../../etc/ or similar)
3. Injecting the traversal payload through vulnerable functionality
4. Successfully modifying directory permissions to enable write access to system directories

The attack requires no user interaction and can be automated once valid credentials are obtained. Compromised or stolen SSLVPN credentials represent the primary barrier to exploitation.

Detection Methods for CVE-2025-32820

Indicators of Compromise

• Unexpected file modifications in system directories such as /etc/, /var/, or configuration directories on SMA appliances
• Log entries showing unusual path patterns containing ../ sequences in SSLVPN user requests
• Unauthorized configuration changes or new files appearing in restricted directories
• Evidence of file permission modifications on critical system paths

Detection Strategies

• Monitor SMA appliance logs for requests containing path traversal patterns (../, ..%2f, %2e%2e/, and encoded variants)
• Implement file integrity monitoring (FIM) on SMA appliances to detect unauthorized changes to system directories
• Review SSLVPN authentication logs for suspicious login patterns or credential abuse
• Deploy network-based detection rules to identify traversal sequences in HTTP/HTTPS traffic to SMA devices

Monitoring Recommendations

• Enable verbose logging on SMA100 series appliances and forward logs to a centralized SIEM for analysis
• Establish baseline file system states on SMA appliances and alert on deviations
• Monitor for unusual administrative actions following SSLVPN user authentication events
• Implement anomaly detection for SSLVPN users accessing functionality outside normal usage patterns

How to Mitigate CVE-2025-32820

Immediate Actions Required

• Apply the security patch from SonicWall immediately by consulting the SonicWall Vulnerability Advisory SNWLID-2025-0011
• Audit all SSLVPN user accounts and disable any unnecessary or suspicious credentials
• Review SMA appliance logs for signs of prior exploitation attempts
• Implement network segmentation to limit the blast radius if an appliance is compromised

Patch Information

SonicWall has released a security update to address this vulnerability. Organizations should immediately consult the official SonicWall Vulnerability Advisory SNWLID-2025-0011 for specific firmware versions and upgrade instructions. Prioritize patching for all internet-facing SMA100 series appliances.

Workarounds

• Restrict SSLVPN access to only essential users and implement strict access control policies
• Enable multi-factor authentication (MFA) for all SSLVPN users to reduce the risk of credential compromise
• Consider implementing web application firewall (WAF) rules to block requests containing path traversal sequences
• If patching is delayed, consider temporarily restricting network access to the SMA management interfaces and limiting SSLVPN connectivity to trusted IP ranges