CVE-2026-21269 in ColdFusion
Summary
by MITRE • 08/12/2026
is affected by a stored Cross-Site Scripting (XSS) vulnerability that could be abused by a low-privileged attacker to inject malicious scripts into vulnerable form fields. Malicious JavaScript may be executed in a victim's browser when they browse to the page containing the vulnerable field. Scope is changed.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a classic stored cross-site scripting flaw that allows attackers to persist malicious code within application storage systems. The security weakness occurs when user input is not properly sanitized or validated before being stored and subsequently rendered back to other users. A low-privileged attacker can exploit this by submitting malicious JavaScript payloads through vulnerable form fields, which are then stored in the application's database or backend storage. When other users access pages containing these tainted fields, their browsers execute the embedded scripts within their context, creating a persistent attack vector that can compromise multiple victims over time.
The technical nature of this vulnerability aligns with CWE-079 - Cross-Site Scripting and maps directly to ATT&CK technique T1531 - Account Access Removal, though more specifically falls under T1203 - Exploitation for Client Execution. The attack chain typically begins with the injection phase where malicious payloads are submitted through web forms, followed by the persistence phase where the code remains stored in the application's data layer, and concludes with the execution phase when victims' browsers render and execute the malicious scripts. This type of vulnerability is particularly dangerous because it can remain undetected for extended periods while continuously affecting users who access the compromised content.
The operational impact extends beyond simple script execution to potentially enable more sophisticated attacks including session hijacking, credential theft, data exfiltration, and browser-based reconnaissance. Attackers can leverage stored XSS to steal authentication tokens, redirect victims to malicious sites, or deploy additional malware payloads through the compromised user sessions. The scope of this vulnerability becomes particularly concerning when considering that it affects form fields, which are commonly used for user-generated content, comment systems, profile information, and other interactive elements within web applications. This creates a wide attack surface where a single insecure input field can serve as an entry point for broader system compromise.
Organizations should implement comprehensive input validation and output encoding mechanisms to prevent this vulnerability class. The recommended mitigations include implementing strict content security policies, employing proper sanitization libraries, utilizing secure coding practices such as HTML escaping, and conducting regular security testing including automated scanning and manual penetration testing. Additionally, organizations should consider implementing web application firewalls, monitoring for suspicious input patterns, and establishing robust incident response procedures to detect and remediate stored XSS vulnerabilities promptly. The defense-in-depth approach should also include user input rate limiting, session management improvements, and regular security awareness training for developers to prevent such flaws in future code development cycles.