CVE-2026-40289Public exploitNetwork attack vector

Unauthenticated session hijacking via originless WebSocket clients

Published Apr 14, 2026 · Updated Apr 14, 2026

Authentication bypass in PraisonAI before 4.5.139 and praisonaiagents before 1.5.140 allows remote attackers to hijack browser sessions. The /ws handshake accepts clients that omit Origin, and start_session routing assigns the first idle extension connection before broadcasting its automation output to the initiator. The bridge must be network-reachable with an idle browser extension connected; exploitation grants browser automation control and exposes page context and results.

CVSS severity9.1
Critical
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in PraisonAI before 4.5.139 and praisonaiagents before 1.5.140 allows remote attackers to hijack browser sessions. The /ws handshake accepts clients that omit Origin, and start_session routing assigns the first idle extension connection before broadcasting its automation output to the initiator. The bridge must be network-reachable with an idle browser extension connected; exploitation grants browser automation control and exposes page context and results.

The record

CVE
CVE-2026-40289
Published
Apr 14, 2026
Updated
Apr 14, 2026
Vendor
PraisonAI
Product
PraisonAI
Classifications
CWE-306, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.5.139

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PraisonAI · PraisonAIversion=< 4.5.139
PraisonAI · praisonaiagentsversion=< 1.5.140

Published CVSS scores

9.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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