VulnerabilityPublished 24 Feb 2026

CVE-2025-11848: Zyxel VMG3625-T50B firmware · NULL Pointer Dereference

Affects Zyxel VMG3625-T50B firmwareSource CVE Database V5

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Not known to be exploited · CVSS 4.9 Medium.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

4.9Medium

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

EPSS: 2.0% chance of exploitation in 30 days – higher than 81% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: High
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: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
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 24 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 Oct 2026.

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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity 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

Affected software

Product	Affected	Fixed in
ZyxelVMG3625-T50B firmware	Affected =<= 5.50(ABPM.9.6)C0	Fixed in–
ZyxelWX3100-T0 firmware	Affected =<= 5.50(ABVL.4.8)C0	Fixed in–

AI-suggested

To mitigate CVE-2025-11848, organizations should first restrict administrative access to Zyxel devices by enforcing strong authentication mechanisms, such as multi-factor authentication and strict password policies. Network segmentation should be applied to isolate management interfaces from general user networks and the internet. Monitoring and logging of HTTP requests to the Wake-on-LAN CGI interface should be implemented to detect anomalous or malformed requests indicative of exploitation attempts. Administrators should regularly audit access logs and review device behavior for signs of instability or crashes. Until a vendor patch is released, consider disabling Wake-on-LAN functionality if not required, or limiting its exposure to trusted networks only. Firmware should be updated promptly once Zyxel releases a patch addressing this vulnerability. Additionally, organizations should implement incident response plans to quickly recover from potential DoS conditions caused by exploitation. Employing network-level protections such as intrusion detection/prevention systems (IDS/IPS) with signatures for malformed HTTP requests targeting these devices can provide additional defense.

Description

A null pointer dereference vulnerability in the Wake-on-LAN CGI program of the Zyxel VMG3625-T50B firmware version through 5.50(ABPM.9.6)C0 and the Zyxel WX3100-T0 firmware versions through 5.50(ABVL.4.8)C0 could allow an authenticated attacker with administrator privileges to trigger a denial-of-service (DoS) condition by sending a crafted HTTP request.

Impact

The primary impact of CVE-2025-11848 is denial of service, which can cause affected Zyxel devices to crash or become unresponsive, disrupting network connectivity and services dependent on these gateways. For organizations relying on these devices for internet access, VPN termination, or network segmentation, this could result in temporary loss of network availability, impacting business operations, communications, and security monitoring. Although the vulnerability does not compromise confidentiality or integrity, the availability disruption could affect critical infrastructure, especially in environments with limited redundancy or manual recovery processes. Attackers with administrator access could leverage this vulnerability to perform targeted DoS attacks, potentially as part of a broader attack chain. The requirement for high privileges limits the attack surface to insiders or attackers who have already compromised administrative credentials, but this does not eliminate risk in environments with weak access controls or credential management. The absence of known exploits reduces immediate risk, but the public disclosure increases the likelihood of future exploitation attempts.

CWE-476NULL Pointer Dereference (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #13OWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
The product dereferences a pointer that it expects to be valid but is NULL.
Implementation
For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
Requirements
Select a programming language that is not susceptible to these issues.
Implementation
Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
OWASP ASVS 4.0.3
V11.1.7 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-null-pointer-dereference-and-command-injection-vulnerabilities-in-certain-4g-lte-5g-nr-cpe-dsl-ethernet-cpe-fiber-onts-security-routers-and-wireless-extenders-02-24-2026 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Mar 2026, 01:55 UTC

WeaknessesCWE-476

Technical details

References

Community reviews

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