CVE-2025-41349: Iest Winplus XSS Vulnerability

CVE-2025-41349 Overview

CVE-2025-41349 is a stored Cross-Site Scripting (XSS) vulnerability [CWE-79] in WinPlus v24.11.27 developed by Informática del Este. The flaw results from missing input validation on the descripcion parameter in a POST request to /WinplusPortal/ws/sWinplus.svc/json/savesolpla_post. An authenticated attacker can inject persistent JavaScript that executes in the browser context of any user who later views the stored content. Successful exploitation enables session cookie theft and action execution on behalf of the victim.

Critical Impact
Authenticated attackers can store malicious scripts that hijack sessions of other WinPlus users through the vulnerable descripcion parameter.

Affected Products

Informática del Este WinPlus v24.11.27
WinPlus Portal web service endpoint /WinplusPortal/ws/sWinplus.svc/json/savesolpla_post
Deployments exposing the WinPlus Portal to authenticated users

Discovery Timeline

2025-11-18 - CVE-2025-41349 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-41349

Vulnerability Analysis

The vulnerability resides in the server-side handler for savesolpla_post, a JSON endpoint exposed by sWinplus.svc. The handler accepts a descripcion field from authenticated users and persists its contents without sanitizing or encoding HTML and JavaScript constructs. When any subsequent user retrieves and renders records containing this field, the browser interprets injected markup as executable script. Because the payload is stored server-side, every viewer of the affected record is impacted until the data is purged. The attack requires an authenticated session but low privileges, and victim interaction when loading the compromised page.

Root Cause

The root cause is improper neutralization of input during web page generation [CWE-79]. The descripcion field is accepted, stored, and later reflected into HTML output without context-aware encoding. The application lacks both input validation on write and output encoding on read, allowing arbitrary HTML and JavaScript to persist in the data layer.

Attack Vector

An authenticated attacker sends a crafted POST request to /WinplusPortal/ws/sWinplus.svc/json/savesolpla_post with a JavaScript payload in the descripcion parameter. The server stores the payload. When another authenticated user, including administrators, loads the page that renders this record, the payload executes in their browser context. The attacker can exfiltrate document.cookie, perform CSRF-equivalent actions, or pivot to further internal attacks. See the INCIBE Security Notice on XSS for additional technical details.

Detection Methods for CVE-2025-41349

Indicators of Compromise

POST requests to /WinplusPortal/ws/sWinplus.svc/json/savesolpla_post containing <script>, onerror=, onload=, or javascript: substrings in the descripcion parameter.
Outbound HTTP requests from user browsers to attacker-controlled domains carrying session cookie values in query strings or request bodies.
Unexpected session reuse from distinct source IPs for the same WinPlus user account within short time windows.

Detection Strategies

Deploy a WAF rule that inspects POST bodies to the savesolpla_post endpoint for HTML tags, event handlers, and script URIs.
Query stored WinPlus records for descripcion values containing angle brackets, javascript:, or encoded script primitives such as %3Cscript.
Correlate authentication logs with anomalous User-Agent or geolocation changes immediately following access to records containing suspicious descripcion values.

Monitoring Recommendations

Enable verbose logging on the WinPlus Portal web service and forward logs to a centralized SIEM for retention and analysis.
Monitor Content Security Policy (CSP) violation reports from browsers accessing the WinPlus Portal to surface inline script execution.
Alert on administrative actions performed shortly after a user viewed records flagged with suspicious descripcion content.

How to Mitigate CVE-2025-41349

Immediate Actions Required

Contact Informática del Este to obtain remediation guidance and apply any vendor-supplied fix for WinPlus v24.11.27.
Audit the WinPlus database for existing descripcion values containing script tags, event handlers, or encoded payloads, and sanitize or remove them.
Restrict access to the WinPlus Portal to trusted networks and reduce the number of accounts with write access to the vulnerable endpoint.

Patch Information

No vendor patch URL is listed in the available advisory data. Review the INCIBE Security Notice on XSS for vendor coordination details and track Informática del Este communications for an updated WinPlus release addressing the descripcion parameter handling.

Workarounds

Deploy a reverse proxy or WAF rule that blocks requests to savesolpla_post containing HTML or JavaScript syntax in the descripcion field.
Enforce a strict Content Security Policy on WinPlus Portal responses to prevent execution of inline and third-party scripts.
Require administrators to use isolated browser profiles when reviewing user-submitted records until a vendor fix is available.

bash

# Example ModSecurity rule to block script payloads in the descripcion parameter
SecRule REQUEST_URI "@contains /WinplusPortal/ws/sWinplus.svc/json/savesolpla_post" \
    "id:1004135,phase:2,deny,status:403,\
     chain,msg:'CVE-2025-41349 WinPlus XSS attempt'"
    SecRule REQUEST_BODY "@rx (?i)(<script|onerror=|onload=|javascript:)" \
        "t:none,t:urlDecodeUni"