VulnerabilityPublished 9 Dec 2025Updated 10 Dec 2025

CVE-2025-65289: Mercury MR816v2 · A Stored Cross Site Scripting (XSS)

Source CVE Database V5

Not known to be exploited · CVSS 6.1 Medium.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

6.1Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

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

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
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: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
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 9 Dec 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 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

Immediately restrict access to the router's management interface to trusted administrative hosts only, using VLAN segmentation or firewall rules to isolate the management network from general LAN access.
Disable DHCP hostname submission from untrusted devices or implement DHCP snooping and validation to prevent malicious hostname injection.
Monitor DHCP logs and router management UI for unusual or suspicious hostname entries indicative of attempted exploitation.
Enforce stronger authentication mechanisms on the router management interface, such as replacing basic authentication with more secure methods (e.g., HTTPS with client certificates or multi-factor authentication) if supported.
Regularly audit router firmware versions and configurations; engage with the vendor for patches or firmware updates addressing this vulnerability.
Educate network administrators about the risks of XSS in management interfaces and the importance of session protection.
Implement network access control (NAC) to limit unauthorized devices on the LAN.
If possible, replace vulnerable routers with models that have robust security features and proper input validation.
Use web application firewalls (WAF) or intrusion detection systems (IDS) tuned to detect suspicious activity related to DHCP hostname injection or management UI access.

Description

A stored Cross site scripting (XSS) vulnerability in the Mercury MR816v2 (081C3114 4.8.7 Build 110427 Rel 36550n) router allows a remote attacker on the LAN to inject JavaScript into the router's management UI by submitting a malicious hostname. The injected script is stored and later executed in the context of an administrator's browser (for example after DHCP release/renew triggers the interface to display the stored hostname). Because the management interface uses weak/basic authentication and does not properly protect or isolate session material, the XSS can be used to exfiltrate the admin session and perform administrative actions.

Impact

For European organizations, this vulnerability poses a significant risk to network infrastructure security, particularly for those using Mercury MR816v2 routers in their internal networks. Successful exploitation can lead to unauthorized administrative control over the router, allowing attackers to modify network configurations, intercept or redirect traffic, and disable security controls. This compromises the confidentiality and integrity of network communications and can facilitate further lateral movement or data exfiltration within the organization. The requirement for LAN access means that attackers must already have some foothold inside the network or physical access, which is common in environments with inadequate network segmentation or guest network controls. The weak authentication and session management exacerbate the risk by making session hijacking feasible. Given the critical role routers play in network security, this vulnerability could disrupt business operations and expose sensitive data. Organizations in sectors with stringent data protection requirements, such as finance, healthcare, and government, are particularly vulnerable to reputational and regulatory consequences if exploited.

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #1OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
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.
Implementation · Architecture and Design
Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages.
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide…
OWASP Cheat Sheets
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.3 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
XSS Using MIME Type Mismatch (opens in a new tab)
DOM-Based XSS (opens in a new tab)
Reflected XSS (opens in a new tab)
Stored XSS (opens in a new tab)
Cross-Site Scripting (XSS) (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

damiri.fr/en/cve/CVE-2025-65289 (opens in a new tab)

Community reviews

Loading reviews…

Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 16 Dec 2025, 17:51 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

Related threats