VulnerabilityPublished 5 Jan 2026

CVE-2025-65328: Mega-Fence · CVE-2025-65328 is a medium severity

Source CVE Database V5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 18% 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:L/I:L/A:N

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

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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 5 Jan 2026
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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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

AI-suggested

Organizations should implement strict validation of the X-Forwarded-For header by verifying that the request has passed through trusted proxies before trusting the client IP value. This can be achieved by configuring Mega-Fence or the web server to only accept XFF headers from known proxy IP addresses. Additionally, consider using alternative methods for client identification, such as mutual TLS or token-based authentication, rather than relying solely on IP allowlists. Network-level protections like Web Application Firewalls (WAFs) can be configured to detect and block suspicious or malformed XFF headers. Regularly update Mega-Fence to the latest version once a patch is released. Finally, audit and monitor logs for anomalies in client IP addresses and review access control policies to reduce reliance on IP-based filtering alone.

Description

CVE-2025-65328 is a medium severity vulnerability in Mega-Fence (webgate-lib. *) versions 25.1.914 and earlier, where the software trusts the first value of the X-Forwarded-For (XFF) HTTP header as the client IP without validating the proxy chain. This allows an attacker to spoof the client IP address by supplying an arbitrary XFF value, potentially bypassing IP-based allowlists and affecting security controls that rely on client IP identification. The vulnerability does not require authentication or user interaction and has a CVSS score of 6.5. While no known exploits are currently reported in the wild, organizations relying on IP-based filtering for access control are at risk. European organizations using affected versions of Mega-Fence should prioritize validation of proxy headers and consider additional network-level protections. Countries with significant deployments of Mega-Fence or critical infrastructure relying on IP allowlists are most likely to be impacted.

Impact

For European organizations, this vulnerability can undermine security controls that depend on accurate client IP identification, such as IP allowlists, geofencing, and rate limiting. Attackers can bypass these controls by spoofing the XFF header, potentially gaining unauthorized access or evading detection. This is particularly concerning for organizations in sectors like finance, government, and critical infrastructure that often rely on IP-based restrictions. The integrity of security logs and audit trails may also be compromised, affecting incident response and forensic investigations. While the vulnerability does not directly impact availability, the loss of trust in client IP data can lead to broader security risks and compliance issues under regulations like GDPR if unauthorized access occurs.

Summary

CVE-2025-65328 is a vulnerability in Mega-Fence's webgate-lib component (version 25.1.914 and prior) that arises from improper validation of the X-Forwarded-For (XFF) HTTP header. The software trusts the first IP address in the XFF header as the true client IP without verifying whether the request passed through trusted proxies. This lack of validation allows an attacker to craft a request with a spoofed XFF header, causing the system to incorrectly identify the attacker-controlled IP as the client IP. This spoofed IP is then propagated into security-relevant state, such as the WG_CLIENT_IP cookie, which may be used for IP-based allowlists or other access control mechanisms. Because the system does not authenticate or validate the proxy chain, attackers can bypass IP allowlists that rely on the client IP for filtering. The vulnerability is classified under CWE-807 (Reliance on Untrusted Inputs in a Security Decision). The CVSS v3.1 base score is 6.5, reflecting network attack vector, low attack complexity, no privileges or user interaction required, and limited confidentiality and integrity impact without availability impact. No patches or known exploits are currently reported, but the vulnerability poses a risk to deployments relying on IP-based security controls.

CWE-807Reliance on Untrusted Inputs in a Security Decision (opens in a new tab)
Base weaknessLikelihood of exploit: HighOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product uses a protection mechanism that relies on the existence or values of an input, but the input can be modified by an untrusted actor in a way that bypasses the protection mechanism.
Architecture and Design · Attack Surface Reduction
Store state information and sensitive data on the server side only.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks…
OWASP Cheat Sheets
Secure Design Principles (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 12 Jan 2026, 21:44 UTC

WeaknessesCWE-807

Technical details

References

Community reviews

Related threats