CVE-2025-27921 in Output Messenger
Summary
by MITRE • 05/05/2025
A reflected cross-site scripting (XSS) vulnerability was discovered in Output Messenger before 2.0.63, where unsanitized input could be injected into the web application’s response. This vulnerability occurs when user-controlled input is reflected back into the browser without proper sanitization or encoding.
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Analysis
by VulDB Data Team • 07/03/2025
This reflected cross-site scripting vulnerability in Output Messenger prior to version 2.0.63 represents a critical security flaw that exposes users to potential malicious code execution through web application interfaces. The vulnerability stems from inadequate input validation and sanitization mechanisms within the application's response handling processes, creating an attack vector where malicious actors can inject harmful scripts into web pages that are subsequently executed by unsuspecting users. The flaw specifically manifests when user-controlled data is directly reflected back to the browser without proper encoding or sanitization measures, allowing attackers to craft malicious payloads that can be delivered through crafted URLs or user interactions.
The technical implementation of this vulnerability aligns with CWE-79, which defines cross-site scripting as a weakness where untrusted data is incorporated into web pages without proper validation or encoding. This particular instance demonstrates how insufficient sanitization of user inputs creates opportunities for attackers to inject malicious scripts that can execute in the context of the victim's browser session. The reflected nature of the vulnerability means that the malicious payload must be crafted specifically for each attack instance and delivered through a URL that includes the malicious input, making it particularly challenging to detect and prevent without proper security controls in place.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to hijack user sessions, steal sensitive information, manipulate application data, or redirect users to malicious websites. Attackers can exploit this weakness to perform session hijacking attacks, where they capture user authentication tokens and credentials, or execute more sophisticated attacks such as credential theft, data exfiltration, or even privilege escalation within the application environment. The reflected nature of the vulnerability means that successful exploitation requires user interaction with a maliciously crafted link, making social engineering a critical component of the attack vector.
Organizations utilizing Output Messenger versions prior to 2.0.63 face significant risk exposure through this vulnerability, particularly in environments where users may encounter untrusted content or where administrative privileges are compromised. The vulnerability can be exploited through various attack scenarios including phishing campaigns, where users are directed to malicious URLs containing crafted payloads, or through compromised web applications that may be serving as attack vectors. Security practitioners should consider implementing proper input validation and output encoding as primary mitigation strategies, following ATT&CK technique T1566.001 for credential access and T1584.003 for phishing attacks that leverage such vulnerabilities. The recommended remediation includes immediate patching to version 2.0.63 or later, implementing proper input sanitization controls, and deploying web application firewalls to detect and prevent malicious payloads from being executed within the application environment.