CVE-2025-40605 is a CWE-23 relative path traversal vulnerability affecting SonicWall Email Security appliances up to version 10.0.33.8195. The flaw allows an attacker to inject crafted directory traversal sequences (e.g., ../) into file system path parameters, bypassing intended path restrictions. This manipulation enables unauthorized access to files and directories outside the designated secure environment. The vulnerability arises from insufficient validation or sanitization of user-supplied input used in file path construction. Exploiting this vulnerability could allow attackers to read sensitive configuration files, logs, or other critical data stored on the appliance, potentially exposing credentials, internal network information, or other confidential data. Although no public exploits have been reported yet, the nature of path traversal vulnerabilities makes them relatively straightforward to exploit remotely if the attacker can reach the vulnerable interface. The affected product is SonicWall Email Security, a widely deployed email filtering and threat protection appliance used by enterprises to secure inbound and outbound email traffic. The vulnerability was published on November 20, 2025, with no CVSS score assigned yet. The lack of authentication requirement and the ability to access arbitrary files elevate the risk profile. SonicWall has not yet released a patch, so organizations must rely on interim mitigations. This vulnerability can compromise the confidentiality and integrity of the appliance and the broader email security infrastructure it supports.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of email security infrastructure. Unauthorized file access could lead to exposure of sensitive data such as email filtering rules, user credentials, or internal network configurations. This could facilitate further attacks like lateral movement, data exfiltration, or disruption of email services. Organizations relying heavily on SonicWall Email Security appliances for regulatory compliance (e.g., GDPR) may face legal and reputational consequences if sensitive personal data is exposed. The ability to exploit this vulnerability without authentication increases the attack surface, especially for organizations with exposed management or email gateway interfaces. Critical sectors such as finance, healthcare, government, and telecommunications in Europe could be particularly impacted due to their reliance on secure email communications and regulatory obligations. The absence of known exploits currently provides a window for proactive mitigation, but the risk of future exploitation remains high.

1. Immediately restrict network access to the SonicWall Email Security management and email gateway interfaces using firewalls or VPNs to limit exposure to trusted administrators only. 2. Monitor appliance logs for unusual file access patterns or attempts to use directory traversal sequences in requests. 3. Implement strict input validation and filtering at network perimeter devices to detect and block suspicious payloads containing directory traversal characters. 4. Regularly back up appliance configurations and critical data to enable recovery in case of compromise. 5. Engage with SonicWall support to obtain any available patches or workarounds and apply them promptly once released. 6. Conduct internal audits of appliance configurations and file permissions to minimize sensitive data exposure. 7. Educate IT and security teams about the vulnerability to enhance detection and response capabilities. 8. Consider deploying additional email security layers or alternative appliances temporarily if patching is delayed. 9. Use network segmentation to isolate the email security appliance from other critical systems to limit lateral movement opportunities.