CVE-2025-5770: WSO2 API Control Plane XSS Vulnerability

CVE-2025-5770 Overview

CVE-2025-5770 is a reflected cross-site scripting (XSS) vulnerability affecting the authentication endpoints of multiple WSO2 products. The flaw stems from missing output encoding, allowing attackers to inject arbitrary JavaScript payloads that the server reflects back in HTTP responses. Successful exploitation requires user interaction, typically by convincing a victim to click a crafted link.

The vulnerability is classified under [CWE-79] Improper Neutralization of Input During Web Page Generation. Impact includes redirection to malicious sites, user interface manipulation, and unauthorized access to data available within the victim's browser context. Session cookies carry the httpOnly flag, which prevents session hijacking through this specific vector.

Critical Impact
Attackers can execute arbitrary JavaScript in a victim's browser session against WSO2 authentication endpoints, enabling phishing, UI redress, and browser-scoped data theft.

Affected Products

WSO2 API Control Plane 4.5.0
WSO2 API Manager 4.2.0, 4.3.0, 4.4.0, 4.5.0
WSO2 Identity Server 6.0.0, 6.1.0, 7.0.0, 7.1.0

Discovery Timeline

2025-11-05 - CVE-2025-5770 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-5770

Vulnerability Analysis

The vulnerability resides in authentication endpoints exposed by WSO2 API Manager, API Control Plane, and Identity Server. These endpoints accept request parameters that are echoed into the HTTP response body without proper HTML or JavaScript context encoding. An attacker can craft a URL containing a JavaScript payload in a vulnerable parameter and deliver it to a target user through phishing, chat, or web links.

When the victim's browser loads the response, the injected script executes within the origin of the WSO2 deployment. Because the payload originates from a trusted authentication domain, the browser applies the security context of that origin to the script. This grants the attacker access to the Document Object Model (DOM), form contents, and any client-side data not protected by httpOnly.

The httpOnly attribute set on session cookies prevents direct cookie theft, limiting session hijacking through this channel. However, the attacker can still submit authenticated requests on the victim's behalf via the browser, capture credentials entered into injected forms, or redirect the user to attacker-controlled infrastructure.

Root Cause

The root cause is missing output encoding in reflected parameters returned by the authentication endpoints. User-supplied input is inserted into the response without context-aware escaping for HTML, attributes, or JavaScript sinks, permitting script tag injection or event handler injection.

Attack Vector

Exploitation requires a network-reachable WSO2 endpoint and victim interaction. The attacker constructs a URL that embeds a JavaScript payload into a vulnerable query parameter of the authentication endpoint. Delivering the link to an authenticated or soon-to-authenticate user triggers script execution in the WSO2 origin when the link is opened.

No verified public proof-of-concept code is available for this issue. Consult the WSO2 Security Advisory WSO2-2025-4270 for vendor-provided technical details.

Detection Methods for CVE-2025-5770

Indicators of Compromise

Requests to WSO2 authentication endpoints containing URL-encoded <script>, javascript:, onerror=, or onload= substrings in query parameters.
HTTP referrers from external domains linking directly into authentication endpoints with unusual parameter values.
Spikes in reflected 200 OK responses on /authenticationendpoint/ paths with abnormally long parameter lengths.

Detection Strategies

Deploy web application firewall (WAF) signatures that inspect authentication endpoint query strings for common XSS payload patterns.
Correlate access logs with outbound DNS or HTTP requests from user workstations following clicks on WSO2 links from external sources.
Review browser and endpoint telemetry for JavaScript execution originating from the WSO2 authentication origin toward unexpected destinations.

Monitoring Recommendations

Enable verbose access logging on WSO2 gateway and Identity Server nodes, retaining full query strings for forensic review.
Monitor Content Security Policy (CSP) violation reports if CSP is enforced, since reflected script execution typically triggers script-src violations.
Alert on user reports of unexpected redirects or login prompts served from WSO2 domains.

How to Mitigate CVE-2025-5770

Immediate Actions Required

Apply the WUM (WSO2 Update Manager) updates referenced in advisory WSO2-2025-4270 to all affected API Manager, API Control Plane, and Identity Server instances.
Restrict external exposure of authentication endpoints where feasible, placing them behind a reverse proxy or WAF that filters XSS payloads.
Enforce a strict Content Security Policy on WSO2 authentication responses to limit inline script execution.

Patch Information

WSO2 has issued fixes through its update mechanism. Refer to the WSO2 Security Advisory WSO2-2025-4270 for the exact update identifiers and installation steps for each affected product version.

Workarounds

Deploy WAF rules blocking script tags, JavaScript URIs, and event handler attributes in parameters submitted to /authenticationendpoint/ paths.
Configure the reverse proxy to strip or reject unexpected query parameters on authentication requests.
Educate users about phishing links pointing to authentication URLs with unusual parameter payloads.

bash

# Example nginx rule to block obvious XSS payloads on WSO2 auth endpoints
location /authenticationendpoint/ {
    if ($args ~* "(<script|javascript:|onerror=|onload=|%3Cscript)") {
        return 403;
    }
    proxy_pass https://wso2-backend;
}