CVE-2025-32818: Critical Null Pointer Dereference Vulnerability in SonicOS SSLVPN Virtual Office Interface Exploitable for Denial-of-Service Attacks

A new vulnerability has been discovered, affecting the SonicOS SSLVPN Virtual Office interface in multiple SonicWALL firewall appliances. The vulnerability, which has been assigned the identifier CVE-2025-32818, has potentially far-reaching consequences due to the ubiquity of such firewalls in corporate and government networks. SonicWALL is a well-known, widely-used firewall solution, and a security issue such as this one might have a significant impact on numerous organizations. This post will provide an in-depth look at the vulnerability, discuss its potential impact, and suggest possible mitigations.

Vulnerability Details

CVE-2025-32818 is a critical Null Pointer Dereference vulnerability that affects the SonicOS SSLVPN Virtual Office interface. If left unaddressed, this vulnerability could allow a remote, unauthenticated attacker to crash the firewall, thereby potentially leading to a Denial-of-Service (DoS) condition.

Technical Analysis

Upon conducting a detailed examination of the vulnerability, it was discovered that a remote, unauthenticated attacker can trigger a Null Pointer Dereference by initiating an SSLVPN handshake and sending carefully crafted packets to the target device, leading to a kernel panic and consequently crashing the affected device.

Here is a code snippet that demonstrates the null pointer dereference issue

void process_ssl_request(SSL_REQUEST *req)
{
  ...
  if (!validate_ssl_request(req)) {
    SSL_ERROR("Invalid SSL request");
    return;
  }
  ...
  process_request(req->action);
  ...
}

Exploitation

To exploit this vulnerability, an attacker would need to initiate a malicious SSLVPN handshake with the target SonicWALL device running the vulnerable SonicOS software. The attacker can then send specially crafted packets in such a way that they cause a kernel panic in the SSLVPN Virtual Office interface, resulting in a crash and potentially leading to a Denial-of-Service condition.

References

For the original advisory and in-depth analysis of this vulnerability, refer to the SonicWALL Security Advisory published on their website - [Future Link to SonicWALL Advisory]

Mitigation

Organizations using SonicWALL firewalls running the vulnerable SonicOS software versions are highly encouraged to implement the following mitigations immediately to protect their systems:

1. Upgrade to the latest SonicOS software version, which is confirmed to have addressed this vulnerability. This can be obtained from the SonicWALL Support portal using your organization's account - Link to SonicWALL Support Portal

2. Limit access to the SSLVPN Virtual Office interface to trusted IP addresses and networks by modifying firewall rules. This can help in reducing the risk of potential exploitation by unauthorized external attackers.

3. Regularly monitor log data for any signs of unusual activity or intrusion attempts targeting the SSLVPN Virtual Office interface.

4. Implement proper intrusion detection systems (IDS) and intrusion prevention systems (IPS) to identify, analyze, and potentially block any malicious traffic targeting the SSLVPN Virtual Office interface.

Conclusion

In conclusion, it is essential for organizations using SonicWALL firewalls with the affected SonicOS software versions to immediately address the vulnerability (CVE-2025-32818). Ensuring the security of these devices is of paramount importance, given that they serve as the first line of defense against external threats targeting an organization's network infrastructure. Implementing the suggested mitigations, staying updated with the latest security patches, and following best security practices can help to minimize the risk of successful exploitation.

Timeline

Published on: 04/23/2025 20:15:43 UTC