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PYSEC-2026-2911

HighCVSS 7.5 / 10
Published Jul 13, 2026·Last modified Jul 13, 2026
Affected Components(0)

No affected components available

Description

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.

<img width="1512" height="947" alt="image" src="https://github.com/user-attachments/assets/3438f3ea-75ec-4978-9dd9-d9a6da42c248" /> <img width="1512" height="571" alt="image" src="https://github.com/user-attachments/assets/ee3313f6-f522-48f7-9c06-e5e265c6aeb4" />

[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

Risk Scores
Base Score
7.5

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information.

Threat Intelligence
6.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.42%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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