Summary
Agent Zero Web UI before version 1.15 does not adequately sanitize user-controlled content in chat messages or file uploads. When the interface reproduces that content, injected JavaScript may execute in the context of an authenticated victim's session.
Agent Zero Web UI before version 1.15 does not adequately sanitize user-controlled content in chat messages or file uploads. When the interface reproduces that content, injected JavaScript may execute in the context of an authenticated victim's session.
Affected context
The vulnerability occurs in Agent Zero Web UI deployments where user-provided chat content or uploaded files are later rendered in the chat interface without sufficient output encoding or sanitization. Risk is greater when an attacker can submit content that is subsequently viewed or reproduced by another authenticated user.
The vulnerability occurs in Agent Zero Web UI deployments where user-provided chat content or uploaded files are later rendered in the chat interface without sufficient output encoding or sanitization. Risk is greater when an attacker can submit content that is subsequently viewed or reproduced by another authenticated user.
Exploit preconditions
- Attack surface: Agent Zero Web UI chat rendering and file-upload workflows
- Required access: Ability to submit or influence chat messages or uploaded file content
- Trigger point: A victim views or causes the affected content to be reproduced in the authenticated web interface
- Why exploitation is possible: User-controlled content is rendered without consistently neutralizing executable browser content
- Attack surface: Agent Zero Web UI chat rendering and file-upload workflows
- Required access: Ability to submit or influence chat messages or uploaded file content
- Trigger point: A victim views or causes the affected content to be reproduced in the authenticated web interface
- Why exploitation is possible: User-controlled content is rendered without consistently neutralizing executable browser content
Why this happens
The underlying bug is improper neutralization of user-controlled input in a web page context. Content from chat messages or file uploads is reproduced without an effective combination of context-aware output encoding, sanitization, and safe rendering controls. This behavior maps to CWE-79: Improper Neutralization of Input During Web Page Generation, commonly known as Cross-Site Scripting.
The underlying bug is improper neutralization of user-controlled input in a web page context. Content from chat messages or file uploads is reproduced without an effective combination of context-aware output encoding, sanitization, and safe rendering controls. This behavior maps to CWE-79: Improper Neutralization of Input During Web Page Generation, commonly known as Cross-Site Scripting.
Potential impact
- Malicious script execution in a victim's browser session
- Unauthorized actions performed with the victim's Agent Zero privileges
- Exposure of data displayed or accessible through the authenticated interface
- Modification of chat content or application state
- Account or workflow compromise, depending on available permissions
- Malicious script execution in a victim's browser session
- Unauthorized actions performed with the victim's Agent Zero privileges
- Exposure of data displayed or accessible through the authenticated interface
- Modification of chat content or application state
- Account or workflow compromise, depending on available permissions
General mitigation guidance
Mitigation generally focuses on treating chat messages, file names, metadata, and uploaded content as untrusted data throughout their lifecycle.
Common defensive patterns include:
- Applying context-aware output encoding whenever user-controlled data is inserted into HTML, attributes, URLs, or scripts
- Using a well-maintained sanitizer with an allowlist when limited markup is required
- Rendering untrusted content as plain text or through isolated safe document viewers
- Validating upload types, names, and metadata while avoiding reliance on client-side checks
- Enforcing a restrictive Content Security Policy as defense in depth
- Limiting authenticated users and service accounts to the least privileges necessary
- Avoiding direct HTML interpretation and unsafe DOM manipulation APIs
Mitigation generally focuses on treating chat messages, file names, metadata, and uploaded content as untrusted data throughout their lifecycle.
Common defensive patterns include:
- Applying context-aware output encoding whenever user-controlled data is inserted into HTML, attributes, URLs, or scripts
- Using a well-maintained sanitizer with an allowlist when limited markup is required
- Rendering untrusted content as plain text or through isolated safe document viewers
- Validating upload types, names, and metadata while avoiding reliance on client-side checks
- Enforcing a restrictive Content Security Policy as defense in depth
- Limiting authenticated users and service accounts to the least privileges necessary
- Avoiding direct HTML interpretation and unsafe DOM manipulation APIs
How teams detect issues like this
Detection approaches can include:
- Static analysis rules for unsafe DOM sinks, direct HTML assignment, and missing context-aware encoding
- Code review checks covering every path from chat or upload input to browser rendering
- Tests using harmless marker strings to verify that untrusted content is encoded or safely sanitized
- Policy enforcement requiring approved sanitization libraries and restrictive browser security headers
- Monitoring for unusual script-like content in submitted messages and uploaded metadata
Automated application security testing and code review tools can help identify common XSS data flows, but should complement manual review of rendering contexts.
Detection approaches can include:
- Static analysis rules for unsafe DOM sinks, direct HTML assignment, and missing context-aware encoding
- Code review checks covering every path from chat or upload input to browser rendering
- Tests using harmless marker strings to verify that untrusted content is encoded or safely sanitized
- Policy enforcement requiring approved sanitization libraries and restrictive browser security headers
- Monitoring for unusual script-like content in submitted messages and uploaded metadata
Automated application security testing and code review tools can help identify common XSS data flows, but should complement manual review of rendering contexts.
Sources
| Source | Link |
|---|---|
| github. | github.com/ |
| github. | github.com/ |
| raw. | raw.githubusercontent.com/ |
| cve. | cve.org/ |
