In 2025, SonicWall appliances became high-value targets for attackers, especially their Secure Mobile Access (SMA) and SSLVPN-enabled platforms. This year brought multiple critical and high-severity vulnerabilities, some already used in live attacks.

What’s more alarming is how attackers chained together multiple CVEs for complete system compromise a stark reminder that remote access devices are top-tier targets in today’s cybersecurity landscape.

The Most Dangerous Chain: CVE-2025-32819 to CVE-2025-32821

Security researchers at Rapid7 revealed a severe exploit chain affecting the SMA 100 series, including models 200, 210, 400, 410, and 500v. This chain gives attackers full root access when executed successfully.

Step 1: Reset the Admin CVE-2025-32819

An attacker with basic VPN credentials can wipe the internal SQLite database and reset the default administrator password. This grants full access to the web management portal.

Step 2: Make System Directories Writable CVE-2025-32820

Next, the attacker exploits a path traversal flaw to make core system directories, like /bin, writable.

Step 3: Full Takeover CVE-2025-32821

Finally, by dropping a crafted executable into the modified directory, they achieve remote code execution as root, gaining full control of the device.

This chain was not theoretical Rapid7 confirmed it had likely been used in real-world attacks based on forensic evidence and private indicators of compromise. SonicWall has patched all three vulnerabilities in firmware version 10.2.1.15-81sv. Organizations are urged to update without delay.

Other Critical SonicWall Vulnerabilities in 2025

In addition to the RCE chain, several other SonicWall CVEs raised red flags this year:

CVE-2025-23006 Unauthenticated RCE in SMA 1000

This zero-day allowed unauthenticated attackers to remotely execute code on SMA 1000 series appliances through unsafe deserialization. Added to the CISA Known Exploited Vulnerabilities catalog, it was actively abused before a fix was released.

CVE-2025-40595 SSRF in the WorkPlace Interface

The SMA 1000’s web interface contained a server-side request forgery flaw, enabling attackers to trick the system into reaching internal resources. Though not publicly exploited, it posed significant internal risk.

CVE-2025-32818 DoS in SSLVPN

SonicWall’s Gen7 and TZ80 devices were affected by a null pointer dereference bug in the SSLVPN interface, which allowed attackers to crash firewalls remotely. This denial-of-service vulnerability didn't require any login and could be triggered by a single malformed request.

Attackers Love VPN Gateways Here's Why

Remote access appliances like SonicWall’s SMA and SSLVPN series are:

• Public-facing

• Privilege-heavy

• Often unpatched for months

These make them perfect entry points for initial access brokers and ransomware gangs. SonicWall's 2025 CVEs reinforce that VPN devices must be treated as high-priority patch assets, not set-and-forget boxes.

What SonicWall Recommends (And You Should Too)

To mitigate ongoing and future risks:

• Update to patched firmware immediately. Delays create windows for attackers.

• Enable multi-factor authentication on all admin and user accounts.

• Restrict portal access to specific IP ranges and disable unused services.

• Review logs for unusual logins or system file activity.

• Use a web application firewall (WAF) where available, especially on exposed portals.

Final Thoughts: Defense Starts at the Edge

I once advised a company to limit the exposure of their VPN interface to the internet.

Their response was, 'It has login protection, a strong password, and brute-force protection anything more is overkill.' They didn’t listen. Months later, they were breached through a zero-day vulnerability a breach that could have been easily prevented had they taken the recommendation seriously

The rise in complex exploit chains and zero-days affecting SonicWall devices paints a broader picture attackers aren’t breaching through the backdoor anymore; they’re walking in the front. VPNs and remote access tools are now prime targets, and with increasing work-from-anywhere models, there’s no excuse for leaving them exposed or unpatched.

Staying ahead requires a mindset shift. Prioritize firmware updates, reduce exposure surfaces, and treat VPN edges like the privileged assets they are.