CVE-2026-39889: PraisonAI Information Disclosure Flaw

CVE-2026-39889 Overview

CVE-2026-39889 is an information disclosure vulnerability in PraisonAI, a multi-agent teams system. Prior to version 4.5.115, the A2U (Agent-to-User) event stream server exposes all agent activity without any authentication controls. The create_a2u_routes() function registers multiple endpoints with no authentication checks, allowing unauthorized access to sensitive agent operational data.

Critical Impact

Unauthenticated attackers can access all agent activity streams, potentially exposing sensitive information processed by AI agents including internal communications, task details, and operational data.

Affected Products

• PraisonAI versions prior to 4.5.115

Discovery Timeline

• 2026-04-08 - CVE-2026-39889 published to NVD
• 2026-04-08 - Last updated in NVD database

Technical Details for CVE-2026-39889

Vulnerability Analysis

This vulnerability falls under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor). The flaw exists in the A2U (Agent-to-User) event stream server component of PraisonAI, which is designed to facilitate communication between AI agents and users.

The core issue stems from the create_a2u_routes() function, which registers several API endpoints without implementing any authentication or authorization mechanisms. These unprotected endpoints include /a2u/info, /a2u/subscribe, /a2u/events/{stream_name}, /a2u/events/sub/{id}, and /a2u/health.

An attacker with network access to a vulnerable PraisonAI deployment can directly access these endpoints to monitor all agent activity in real-time. This could include sensitive information being processed by the multi-agent system, task assignments, inter-agent communications, and any data flowing through the event streams.

Root Cause

The root cause is missing authentication middleware on the A2U event stream endpoints. The create_a2u_routes() function registers routes directly without wrapping them in authentication decorators or middleware that would validate user credentials before granting access. This represents a fundamental secure-by-default design failure where sensitive operational endpoints were exposed without access controls.

Attack Vector

The vulnerability is exploitable over the network without requiring any authentication credentials or user interaction. An attacker needs only network connectivity to the PraisonAI instance to exploit this flaw.

The attack flow involves:

1. Identifying a PraisonAI deployment with the A2U server exposed
2. Accessing the /a2u/info endpoint to enumerate available streams
3. Subscribing to agent event streams via /a2u/subscribe or /a2u/events/{stream_name}
4. Passively collecting all agent activity data without triggering security alerts

Since no authentication is required, the attacker can silently monitor all agent communications and activities. For more technical details, refer to the GitHub Security Advisory.

Detection Methods for CVE-2026-39889

Indicators of Compromise

• Unexpected external connections to A2U endpoints (/a2u/info, /a2u/subscribe, /a2u/events/*)
• High volume of requests to event stream endpoints from unrecognized IP addresses
• Connections to the A2U server from outside trusted network ranges
• Unusual subscription patterns or bulk data retrieval from agent event streams

Detection Strategies

• Implement network monitoring for connections to PraisonAI A2U endpoints from unauthorized sources
• Deploy web application firewall (WAF) rules to detect and alert on unauthenticated access attempts to /a2u/* paths
• Enable detailed access logging for all A2U server endpoints and review for anomalous patterns
• Configure intrusion detection systems (IDS) to alert on reconnaissance activity targeting PraisonAI services

Monitoring Recommendations

• Establish baseline network traffic patterns for legitimate A2U endpoint usage
• Monitor for connections to the A2U server originating from public IP addresses or untrusted networks
• Set up alerts for new subscription requests to agent event streams
• Review access logs regularly for patterns indicative of data exfiltration or unauthorized monitoring

How to Mitigate CVE-2026-39889

Immediate Actions Required

• Upgrade PraisonAI to version 4.5.115 or later immediately
• If immediate upgrade is not possible, restrict network access to A2U endpoints using firewall rules
• Audit access logs for any suspicious activity that may indicate prior exploitation
• Review any data processed by agents during the exposure window for sensitive information leakage

Patch Information

The vulnerability has been fixed in PraisonAI version 4.5.115. Users should upgrade to this version or later to remediate the vulnerability. Refer to the GitHub Security Advisory for official patch information and release notes.

Workarounds

• Implement network-level access controls to restrict A2U endpoint access to trusted IP ranges only
• Deploy a reverse proxy with authentication in front of the PraisonAI A2U server
• If the A2U functionality is not required, disable or remove the A2U routes from the deployment
• Segment the network to isolate PraisonAI deployments from untrusted network zones

# Example: Restrict access to A2U endpoints using iptables
# Allow only trusted internal network (192.168.1.0/24) to access PraisonAI port
iptables -A INPUT -p tcp --dport 8080 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP