CVE-2025-40601VulnerabilityPublished 20 Nov 2025

CVE-2025-40601: SonicWall SonicOS · Stack-based Buffer Overflow

Affects SonicWall SonicOSSource CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.9% chance of exploitation in 30 days – higher than 59% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 20 Nov 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

AI-suggested

1. Immediately inventory all SonicWall devices to identify affected SonicOS versions (7.3.0-7012 and older, 8.0.2-8011 and older). 2. Monitor SonicWall vendor communications closely for official patches or firmware updates addressing CVE-2025-40601 and apply them promptly upon release. 3. Restrict access to the SSLVPN service by implementing network-level controls such as IP whitelisting, VPN gateway access control lists, or geo-blocking to limit exposure to trusted sources only. 4. Employ intrusion detection/prevention systems (IDS/IPS) with updated signatures to detect anomalous SSLVPN traffic patterns indicative of exploitation attempts. 5. Consider temporarily disabling SSLVPN services if feasible until patches are applied, especially in high-risk environments. 6. Enhance logging and monitoring on SonicWall devices to capture crash events and unusual connection attempts for rapid incident response. 7. Conduct regular backups of firewall configurations to enable quick restoration in case of crashes. 8. Educate network administrators on the vulnerability and recommended response procedures. 9. Evaluate network segmentation to isolate critical assets from VPN endpoints to limit impact of potential DoS. 10. Engage with SonicWall support for guidance and potential workarounds if patches are delayed.

Description

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.

Impact

For European organizations, the impact of CVE-2025-40601 can be significant due to the widespread use of SonicWall firewalls in corporate, governmental, and critical infrastructure networks. A denial of service on perimeter firewalls can disrupt secure remote access, impede business continuity, and expose networks to further attacks during downtime. Industries reliant on continuous VPN connectivity, such as finance, healthcare, and manufacturing, may experience operational interruptions. Additionally, firewall outages can degrade incident response capabilities and increase exposure to other threats. Given the vulnerability requires no authentication and no user interaction, attackers can remotely target exposed SSLVPN services with relative ease. This elevates the risk of widespread disruption, especially in organizations with internet-facing SonicWall SSLVPN endpoints. The lack of known exploits currently provides a window for proactive mitigation, but the potential for rapid weaponization exists. European entities with strict regulatory requirements for network availability and data protection may face compliance challenges if disruptions occur. Overall, the vulnerability threatens availability of critical network security infrastructure, potentially impacting confidentiality and integrity indirectly by disabling protective controls.

CWE-121Stack-based Buffer Overflow (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #14
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Implementation
Implement and perform bounds checking on input.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

psirt.global.sonicwall.com/vuln-detail/SNWLID-2025-0016 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 27 Nov 2025, 13:47 UTC

WeaknessesCWE-121

Technical details

References

Community reviews

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