CVE-2025-11278: AllStarLink Supermon XSS Vulnerability

CVE-2025-11278 Overview

CVE-2025-11278 is a cross-site scripting (XSS) vulnerability affecting AllStarLink Supermon versions up to 6.2. The flaw resides in the AllMon2 component and allows remote attackers to inject arbitrary script content that executes in the context of a victim's browser. Exploitation requires user interaction, such as convincing a target to visit a crafted link or page. The exploit has been publicly disclosed. The vendor was contacted but did not respond, and the affected product line is no longer supported by the maintainer. The vulnerability is categorized under CWE-79, Improper Neutralization of Input During Web Page Generation.

Critical Impact
Remote attackers can execute arbitrary JavaScript in the context of Supermon users, potentially hijacking sessions or manipulating monitoring data on unsupported deployments.

Affected Products

AllStarLink Supermon versions up to and including 6.2
Supermon AllMon2 component
Deployments running end-of-life Supermon builds without vendor support

Discovery Timeline

2025-10-05 - CVE-2025-11278 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-11278

Vulnerability Analysis

The vulnerability is a reflected or stored cross-site scripting weakness within the AllMon2 component of AllStarLink Supermon. Supermon is a web-based monitoring and management interface for AllStarLink amateur radio linking nodes. The AllMon2 component processes user-controllable input and returns it to the browser without sufficient output encoding, allowing an attacker to embed HTML or JavaScript payloads that the browser then renders as executable code.

Because the attack vector is network based and user interaction is required, an attacker typically delivers a crafted URL or induces a target to load a page that triggers the injection. Successful exploitation runs in the origin of the Supermon interface, granting access to session cookies, DOM contents, and any administrative actions the victim is authorized to perform. The EPSS probability is 0.31%.

Root Cause

The root cause is the failure to neutralize special HTML and JavaScript metacharacters in input handled by AllMon2 before returning that input inside the HTML response. Missing contextual output encoding on parameters rendered into the page enables script injection consistent with [CWE-79].

Attack Vector

The attack is initiated over the network and requires the victim to interact with attacker-controlled content, for example by clicking a crafted link that supplies a malicious query parameter to the Supermon interface. When the response reflects the payload, the browser executes it. Confidentiality of the parent system is unaffected in the CVSS assessment, but integrity of data rendered in the browser session is impacted.

No verified proof-of-concept code has been published to a curated exploit repository. See the VulDB CTI Advisory #327012 for additional technical context.

Detection Methods for CVE-2025-11278

Indicators of Compromise

HTTP requests to Supermon AllMon2 endpoints containing <script>, onerror=, javascript:, or URL-encoded equivalents such as %3Cscript%3E
Web server access logs showing unusual query string parameters targeting AllMon2 pages
Browser console errors or unexpected outbound requests from administrator sessions viewing Supermon pages

Detection Strategies

Deploy a web application firewall rule set that flags reflected script metacharacters against Supermon URLs
Enable a strict Content Security Policy (CSP) in report-only mode to surface script execution originating from unexpected sources
Review referrer headers and access patterns for links directing users into AllMon2 with abnormal parameters

Monitoring Recommendations

Aggregate Supermon HTTP access logs and alert on payload signatures associated with XSS attempts
Monitor administrator account activity for anomalous actions performed shortly after clicking external links
Track outbound connections from browsers that render the Supermon interface to identify script-triggered data exfiltration

How to Mitigate CVE-2025-11278

Immediate Actions Required

Restrict network access to Supermon so it is reachable only from trusted management networks or over a VPN
Require administrators to log out of Supermon when not actively using the interface to shrink the session window available to attackers
Warn users not to click untrusted links that reference Supermon hostnames or AllMon2 endpoints

Patch Information

No official patch is available. The vendor did not respond to disclosure, and the affected Supermon branch is no longer supported by the maintainer. Operators should plan migration to a maintained monitoring solution or a supported successor project.

Workarounds

Front the Supermon interface with a reverse proxy that enforces a strict Content Security Policy blocking inline scripts and unauthorized origins
Apply web application firewall rules to strip or reject requests containing HTML or JavaScript metacharacters targeting AllMon2
Disable or firewall off the AllMon2 component if it is not required for operations
Isolate the Supermon host on a management VLAN reachable only from administrator workstations

bash

# Example nginx snippet enforcing CSP and blocking obvious XSS payloads
location /allmon2/ {
    add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; frame-ancestors 'none'" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-Frame-Options "DENY" always;

    if ($args ~* "(<|%3C)script|javascript:|onerror=|onload=") {
        return 403;
    }

    proxy_pass http://127.0.0.1:8080;
}