MervinPraison PraisonAI up to 4.5.127 Flask API Endpoint src/praisonai/api.py _sanitize_html cross site scripting

Summaryinfo

A vulnerability identified as problematic has been detected in MervinPraison PraisonAI up to 4.5.127. Affected by this vulnerability is the function _sanitize_html of the file src/praisonai/api.py of the component Flask API Endpoint. This manipulation causes cross site scripting. This vulnerability is registered as CVE-2026-40112. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in MervinPraison PraisonAI up to 4.5.127. It has been declared as problematic. Affected by this vulnerability is the function _sanitize_html of the file src/praisonai/api.py of the component Flask API Endpoint. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

PraisonAI is a multi-agent teams system. Prior to 4.5.128, the Flask API endpoint in src/praisonai/api.py renders agent output as HTML without effective sanitization. The _sanitize_html function relies on the nh3 library, which is not listed as a required or optional dependency in pyproject.toml. When nh3 is absent (the default installation), the sanitizer is a no-op that returns HTML unchanged. An attacker who can influence agent input (via RAG data poisoning, web scraping results, or prompt injection) can inject arbitrary JavaScript that executes in the browser of anyone viewing the API output. This vulnerability is fixed in 4.5.128.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-40112 since 04/09/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 4.5.128 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• MervinPraison

Name

• PraisonAI

Version

• 4.5.127

Website

• Product: https://github.com/MervinPraison/PraisonAI/

CPE 2.3info

• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion