CVE-2026-40289

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 72% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this weekElevated
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.1Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

PraisonAI is a multi-agent teams system. In versions below 4.5.139 of PraisonAI and 1.5.140 of praisonaiagents, the browser bridge (praisonai browser start) is vulnerable to unauthenticated remote session hijacking due to missing authentication and a bypassable origin check on its /ws WebSocket endpoint. The server binds to 0.0.0.0 by default and only validates the Origin header when one is present, meaning any non-browser client that omits the header is accepted without restriction. An unauthenticated network attacker can connect, send a start_session message, and the server will route it to the first idle browser-extension WebSocket (effectively hijacking that session) and then broadcast all resulting automation actions and outputs back to the attacker. This enables unauthorized remote control of connected browser automation sessions, leakage of sensitive page context and automation results, and misuse of model-backed browser actions in any environment where the bridge is network-reachable. This issue has been fixed in versions 4.5.139 of PraisonAI and 1.5.140 of praisonaiagents.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
72(Attend)
EG Risk 72/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity91% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
28%
KEV
Not listed

Published

April 14, 2026

Last Modified

April 20, 2026

Advisory Details (1)

Auto-updated May 20, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

PraisonAI Browser Server allows unauthenticated WebSocket clients to hijack connected extension sessions · Advisory · MervinPraison/PraisonAI · GitHub

https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-8x8f-54wf-vv92

Affected Packages

(2 across 1 ecosystem)
PyPI(2)
PackageVulnerable rangeFixed inDependents
praisonai0.0.1 ... 4.5.98 (695 versions)4.5.139—
praisonaiagents0.0.1 ... 1.5.99 (519 versions)1.5.140—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 39× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-26 14:54 UTCEPSS rescore
  2. 2026-07-26 14:54 UTCEPSS rescore
  3. 2026-07-25 14:18 UTCEPSS rescore
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  9. 2026-07-23 03:11 UTCEG score recompute
  10. 2026-07-22 14:08 UTCEPSS rescore
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  12. 2026-07-20 18:32 UTCOSV refresh
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  1. 2026-07-09 19:10 UTCEPSS rescore
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  22. 2026-06-21 14:56 UTCEPSS rescore
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  71. 2026-05-20 17:30 UTCEG score recompute
  72. 2026-05-20 11:22 UTCEPSS rescore
  73. 2026-05-20 11:22 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-40289?
CVE-2026-40289 is a critical vulnerability published on April 14, 2026. PraisonAI is a multi-agent teams system. In versions below 4.5.139 of PraisonAI and 1.5.140 of praisonaiagents, the browser bridge (praisonai browser start) is vulnerable to unauthenticated remote session hijacking due to missing authentication and a bypassable origin check on its /ws WebSocket…
When was CVE-2026-40289 disclosed?
CVE-2026-40289 was first published in the National Vulnerability Database on April 14, 2026, with the most recent update on April 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40289 actively exploited?
CVE-2026-40289 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 71.8% of all scored CVEs.
What is the CVSS score of CVE-2026-40289?
CVE-2026-40289 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-40289?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40289, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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