CVE-2026-7498: DernekWeb Stored XSS Vulnerability

CVE-2026-7498 Overview

CVE-2026-7498 is a stored cross-site scripting (XSS) vulnerability affecting Basamak Information Technology Consulting and Organization Trade Ltd. Co. DernekWeb. The flaw allows attackers to inject persistent malicious scripts into the web application, which execute in the browsers of users who view the affected pages. The issue affects all DernekWeb versions through build 30122025. The vulnerability is classified under CWE-79 and was published to the National Vulnerability Database on 2026-05-18.

Critical Impact
Authenticated or unauthenticated attackers can store malicious JavaScript that executes in victim browsers, enabling session theft, account takeover, and content manipulation across the DernekWeb application.

Affected Products

Basamak DernekWeb through build 30122025
All deployments of DernekWeb prior to the vendor's remediation
Web-facing DernekWeb instances accessible to untrusted users

Discovery Timeline

2026-05-18 - CVE-2026-7498 published to NVD
2026-05-18 - Last updated in NVD database

Technical Details for CVE-2026-7498

Vulnerability Analysis

The vulnerability stems from improper neutralization of user-supplied input during web page generation in the DernekWeb application. Attacker-controlled input is persisted by the application and later rendered in HTML responses without adequate output encoding or sanitization. Because the payload is stored server-side, every user who loads the affected page executes the injected script in their authenticated session context.

Exploitation requires user interaction, as a victim must visit the page containing the stored payload. Once triggered, the script runs with the privileges of the viewing user's session and can read cookies, manipulate the Document Object Model (DOM), issue authenticated requests, and exfiltrate data to attacker-controlled hosts.

Root Cause

The root cause is missing or insufficient output encoding when rendering user-controllable fields into HTML contexts. The application accepts input through forms or user-editable resources, stores the raw value, and later inlines it into responses without context-aware escaping. This pattern aligns with CWE-79: Improper Neutralization of Input During Web Page Generation.

Attack Vector

An attacker submits a payload containing HTML or JavaScript through a DernekWeb input field that is later rendered to other users. When victims load the affected page, the browser parses the payload as executable script. The attacker can hijack sessions, perform actions on behalf of administrators, deface content, or pivot to internal resources. Refer to the Siber Güvenlik Notification for vendor-coordinated details.

Detection Methods for CVE-2026-7498

Indicators of Compromise

Stored content fields containing <script> tags, javascript: URIs, or event handlers such as onerror= and onload=
Outbound HTTP requests from user browsers to unknown domains immediately after rendering DernekWeb pages
Unexpected administrative actions originating from valid sessions shortly after viewing user-submitted content

Detection Strategies

Review DernekWeb database tables and content stores for HTML or JavaScript payloads in fields intended to hold plain text
Inspect web server access logs for POST requests containing encoded script tags or HTML entities targeting input endpoints
Deploy Content Security Policy (CSP) violation reporting to identify inline script execution attempts in production

Monitoring Recommendations

Forward DernekWeb application and web server logs to a centralized analytics platform for correlation and retention
Alert on anomalous JavaScript-related strings in stored content and on sudden spikes in outbound requests from authenticated user sessions
Monitor administrator account activity for actions triggered immediately after viewing user-generated pages

How to Mitigate CVE-2026-7498

Immediate Actions Required

Identify all DernekWeb deployments running builds at or before 30122025 and restrict public access where feasible
Audit stored content for existing malicious payloads and remove or neutralize any injected scripts
Force password resets and session invalidation for administrative accounts that may have viewed attacker-controlled content

Patch Information

Consult the Siber Güvenlik Notification (TR-26-0258) for vendor remediation guidance. Apply the fixed release from Basamak Information Technology Consulting and Organization Trade Ltd. Co. as soon as it becomes available, and verify that input handling routines perform context-aware output encoding.

Workarounds

Implement a strict Content Security Policy that disallows inline scripts and restricts script sources to trusted origins
Place DernekWeb behind a web application firewall (WAF) with rules that block common XSS payload patterns
Limit content submission privileges to vetted users and require manual review of user-generated content before publication

bash

# Example restrictive Content-Security-Policy header for DernekWeb responses
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'; frame-ancestors 'none'; report-uri /csp-report";
add_header X-Content-Type-Options "nosniff";
add_header X-Frame-Options "DENY";