Summary

Vulnerability: Stored DOM XSS via Blog Tag Name (Persistent Payload Injection)

• Stored Cross-Site Scripting via Unsanitized Blog Tag Name in Blog Management

Description

The application fails to properly sanitize user-controlled input when creating or editing blog tags. An attacker can inject a malicious JavaScript payload into the tag name field, which is then stored server-side.

This stored payload is later rendered unsafely across public tag pages and administrative interfaces without proper output encoding, leading to stored cross-site scripting (XSS).

Affected Functionality

• Blog tag creation functionality
• Blog tag editing functionality
• Blog tag storage and retrieval logic

Attack Scenario

• An attacker creates or edits a blog tag name to include a malicious XSS payload.
• The application stores this value without sanitization or encoding.
• The payload persists and executes whenever the tag name is rendered in affected views.

Impact

• Persistent Stored XSS
• Execution of arbitrary JavaScript in victims’ browsers
• Privilege escalation when viewed by administrators or privileged users
• Full administrator account takeover
• Full account takeover across all roles
• Full compromise of the entire application

Endpoints:

• /backend/blogs/tags/
• /blog/{id}

Steps To Reproduce (POC)

1. Go to the Blog Tags management page
2. Create or edit a tag and insert an XSS payload into the tag name such as: <img src=x onerror=alert(document.domain)>
3. Save the tag
4. View a public blog page or the administrative interface where the tag is rendered
5. Notice the XSS payload executing automatically

Remediation

• Avoid unsafe DOM manipulation methods: Do not use .html(), innerHTML, or similar sink functions in client-side JavaScript or server-side templating (e.g., PHP). Even when user input flowing into these sinks is not immediately apparent, they can introduce Cross-Site Scripting (XSS) vulnerabilities that an attacker may exploit.

• Apply output encoding: Implement HTML entity encoding on all user-controlled data before rendering it in the browser. This helps neutralize potentially malicious input.