CVE-2026-48307: ColdFusion Reflected XSS Vulnerability – HIGH Severity Analysis

Technical summary

This reflected XSS vulnerability (CWE-79) exists in ColdFusion's web application layer where user-supplied input is not properly sanitized before being reflected back in HTTP responses. The attack vector is adjacent network (AV:A), meaning an attacker must be on the same network segment or have control over a network path to the target. User interaction is required—the victim must click a malicious link. Critically, the scope is changed (S:C), indicating that the vulnerability can affect resources beyond the vulnerable component, enabling an attacker to impact other users or services. The CVSS 3.1 vector (8.8 HIGH) reflects high impact on confidentiality, integrity, and availability.

Business impact

A successful exploit could allow attackers to compromise user sessions, steal authentication credentials, or redirect users to phishing sites. In business-critical ColdFusion deployments—common in enterprise applications, content management, and e-commerce—this could result in unauthorized data access, transaction fraud, or reputational damage. Since the scope is changed, an attacker could potentially pivot to affect other applications or users sharing the same network or application infrastructure. Organizations relying on ColdFusion for customer-facing or internal applications face material risk if users are socially engineered into clicking malicious links.

Affected systems

Adobe ColdFusion versions 2025.9, 2023.20, and all earlier releases are vulnerable. This includes both Windows and Linux deployments of ColdFusion. Organizations should audit all ColdFusion instances to determine their current version and prioritize patching based on network exposure and user population at risk.

Exploitability

While the vulnerability requires user interaction (clicking a malicious link), this is a relatively low bar for attack feasibility. Attackers can craft convincing phishing emails, embed malicious links in forum posts, or use social engineering to trick users into clicking. The adjacent network vector suggests the attack requires network proximity or control, which may limit exploitation in some environments but not others. This is not currently tracked in CISA's Known Exploited Vulnerabilities catalog, though reflected XSS vulnerabilities are typically straightforward to weaponize once the injection point is identified.

Remediation

Adobe will release security patches for affected ColdFusion versions. Organizations should immediately apply patches when available. Interim measures include implementing Web Application Firewalls (WAF) with input validation and output encoding rules, restricting network access to ColdFusion administrative interfaces, and conducting user awareness training to reduce the likelihood of clicking malicious links. Review and update any custom ColdFusion code to ensure proper input sanitization and output encoding.

Patch guidance

Monitor Adobe's security advisories and the ColdFusion release notes for patched versions addressing CVE-2026-48307. Apply patches promptly to production and non-production environments. Test patches in a staging environment first to ensure compatibility with existing applications. For organizations unable to patch immediately, prioritize restricting network access to vulnerable ColdFusion instances and implement additional logging to detect exploitation attempts.

Detection guidance

Monitor web application logs and WAF logs for anomalous patterns including script tags, encoded payloads, or unusual parameter values in requests to ColdFusion applications. Look for HTTP responses containing unencoded user input or script content. Network-based intrusion detection systems (IDS) may flag malicious payloads. Consider implementing Content Security Policy (CSP) headers to mitigate reflected XSS impact even if the injection occurs. Monitor for unusual outbound connections from affected ColdFusion servers that might indicate successful exploitation.

Why prioritize this

Despite not yet appearing in CISA's KEV catalog, this vulnerability warrants immediate attention due to its HIGH CVSS score (8.8), broad impact scope, and the widespread use of ColdFusion in enterprise environments. The changed scope means an attacker could compromise multiple users or systems. Organizations should prioritize patching in the following order: (1) internet-facing ColdFusion applications, (2) applications handling sensitive data, (3) internal applications with high user counts.

Risk score, explained

The CVSS 3.1 score of 8.8 (HIGH) reflects the combination of high impact across all three security dimensions (confidentiality, integrity, availability), a changed scope enabling cross-boundary impact, and a relatively accessible attack vector for users on the same network. The score is tempered only by the requirement for user interaction. In isolated or air-gapped environments, risk may be lower; in internet-facing or heavily trafficked deployments, risk approaches critical.

Frequently asked questions