CVE-2026-31382 in Assist
Summary
by MITRE • 03/20/2026
The error_description parameter is vulnerable to Reflected XSS. An attacker can bypass the domain's WAF using a Safari-specific onpagereveal payload.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 03/26/2026
The vulnerability identified as CVE-2026-31382 represents a critical reflected cross-site scripting flaw within the error_description parameter of a web application. This weakness allows malicious actors to inject client-side scripts that execute in the context of other users' browsers when they encounter the reflected payload. The vulnerability specifically impacts applications that process user input through the error_description parameter without adequate sanitization or output encoding mechanisms. The reflected nature of this XSS vulnerability means that the malicious script is embedded within the application's response, typically through a URL parameter, making it particularly dangerous as it can be delivered through phishing emails, malicious links, or compromised websites. The vulnerability's classification as a reflected XSS aligns with CWE-79 which defines this as a type of injection vulnerability where malicious scripts are reflected off a web server to a victim's browser.
The operational impact of this vulnerability extends beyond traditional XSS exploitation methods, as attackers can bypass standard web application firewalls using Safari-specific payloads that leverage the onpagereveal event handler. This technique exploits browser-specific behaviors and security model differences, particularly within Apple's Safari browser implementation. The onpagereveal payload demonstrates sophisticated evasion capabilities that can circumvent WAF signatures designed for more common XSS attack vectors. This bypass mechanism represents a significant concern for organizations relying solely on WAF protection, as it reveals weaknesses in traditional security controls and highlights the need for more comprehensive application security measures. The vulnerability's ability to bypass WAF protection through browser-specific techniques aligns with ATT&CK technique T1566.001 which covers spearphishing attachments and T1566.002 for spearphishing links, as attackers can leverage these vulnerabilities to deliver malicious payloads that evade detection.
Organizations affected by this vulnerability face substantial risks including unauthorized access to user sessions, data theft, privilege escalation, and potential system compromise through session hijacking or credential theft. The Safari-specific nature of the bypass payload indicates that attackers may be targeting Apple ecosystem users specifically, potentially leveraging the browser's unique security model to execute attacks that would otherwise be blocked by traditional security controls. This vulnerability can be exploited to perform actions such as stealing cookies, redirecting users to malicious sites, defacing web pages, or executing arbitrary JavaScript code within the victim's browser context. The attack vector typically involves crafting a malicious URL containing the XSS payload and delivering it to victims through social engineering campaigns or compromised websites. Security teams must implement comprehensive input validation, output encoding, and proper content security policies to address this vulnerability. The recommended mitigations include implementing strict input sanitization, employing proper output encoding for all user-supplied data, configuring appropriate content security policies, and deploying WAF rules specifically designed to detect and block Safari-specific XSS payloads. Additionally, organizations should consider implementing additional security controls such as browser security headers, secure coding practices, and regular security testing to prevent similar vulnerabilities from being introduced in future application versions.