TIRESIS/Forecast/CVE-2025-40601
MEDIUM RISK

CVE-2025-40601

A Stack-based buffer overflow vulnerability in the SonicOS SSLVPN service allows a remote unauthenticated attacker to cause Denial of Service (DoS), which could cause an impacted firewall to crash.

SMB Attack Probability Score
20/100medium
Weighted: EPSS · CISA KEV · SMB stack prevalence · exploit maturity · CVSS vector
CVSS v3
7.5
EPSS (30d)
0.04%
SMB Exposure
43.4/100
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
🔓
SMB Impact
How this vulnerability affects a real small business
1
How this breaks an SMB

Firewall or VPN compromise gives attackers full internal network access — no further credentials needed. All connected systems are immediately at risk.

2
Typical real-world scenario

Automated scanner identifies the exposed appliance. Within hours, lateral movement begins: file servers, domain controller, and backup systems are reached.

3
Estimated downtime & cost
Est. downtime
3–7 days
Business cost range
€15K–€80K
4
What IT should check this week
Is this appliance directly internet-facing?
Is firmware/OS version patched to latest?
Are admin consoles accessible without MFA?
Is network segmentation between IT and OT/servers active?
Scenarios are generated based on software category and CVE characteristics. Cost ranges reflect SMB incidents in TIRESIS incident database.
Threat Evolution Timeline
From disclosure to predicted exploitation — 3 events
1 predicted
📋
20 Nov 2025
Vulnerability disclosed
CVE published by NVD with CVSS 7.5 (HIGH)
📍
TODAY
Today
EPSS: 0.0% probability of exploitation in next 30 days. SMB Risk Score: 20/100
Forecast →
29 Jun 2026◈ predicted · in 60 days
Predicted: widespread patch adoption
Low EPSS suggests limited active exploitation. Most organizations expected to patch in routine maintenance cycle.
◈ Predicted eventsare estimates based on EPSS score, exploit maturity, and historical CVE progression patterns. They are not guaranteed outcomes.
Affected Products
sonicostz270nsa 3800tz680nssp 13700tz470tz280nssp 15700nsa 3700tz670nsa 4700nsa 2800nssp 11700nsa 6700nsa 5700nsa 5800nsv870tz380tz580tz270wtz80nsa 4800tz570wtz370
Remediation & References
What to do
🌐No authentication required — restrict external access nowhigh

This vulnerability can be exploited remotely without credentials or user interaction. Until patched: block access to the affected service from the internet using firewall rules or ACLs. Only allow access from trusted IPs.

🔐Update VPN client/gateway firmware immediatelyhigh

VPN gateways are the primary attack surface for ransomware initial access. Apply the vendor patch immediately. If patching is delayed, consider temporarily disabling the VPN and using an alternative access method, or restricting access to specific IP ranges.

🔥Apply firewall firmware update via vendor PSIRT advisoryhigh

Firewall vulnerabilities are high-value targets — they sit at the network perimeter. Download the patched firmware from the vendor's official PSIRT page. Schedule an off-hours maintenance window to avoid business disruption during the update.

🛡Enable multi-factor authentication on VPNmedium

MFA on VPN significantly reduces the risk of credential-based exploitation. Even if this CVE is patched, MFA remains a critical defence layer for remote access.

⚙️Disable management interface access from the internetmedium

The firewall management portal (web UI, SSH, API) should never be exposed directly to the internet. Restrict management access to internal IPs or a dedicated management VLAN only.

NVD Full Entry ↗Official vulnerability detail, CVSS vectors, CPE listEPSS Score ↗Exploit Prediction Scoring System — FIRST.orgMitre CVE ↗MITRE CVE Program official entry
Vendor & Exploit References
Scoring Methodology

SMB Attack Probability Score weights: EPSS exploit likelihood (35%), CISA KEV active exploitation (25%), SMB stack prevalence (20%), exploit maturity (10%), CVSS network vector complexity (10%). Impact scenarios are derived from software category and historical SMB incident patterns. Scores recompute daily.