CVE-2026-39890Public exploitNetwork attack vector

Remote code execution via unsafe YAML deserialization

Published Apr 8, 2026 · Updated Apr 8, 2026

Unsafe YAML deserialization in PraisonAI before 4.5.115 allows remote attackers to execute arbitrary code through an agent file upload. The AgentService.loadAgentFromFile method passes attacker-controlled YAML to js-yaml load without a safe schema, so !!js/function payloads execute during parsing. Exploitation requires an exposed API path or authenticated agent-upload rights and grants server-process code execution when the agent loads.

CVSS severity9.8
Critical
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unsafe YAML deserialization in PraisonAI before 4.5.115 allows remote attackers to execute arbitrary code through an agent file upload. The AgentService.loadAgentFromFile method passes attacker-controlled YAML to js-yaml load without a safe schema, so !!js/function payloads execute during parsing. Exploitation requires an exposed API path or authenticated agent-upload rights and grants server-process code execution when the agent loads.

The record

CVE
CVE-2026-39890
Published
Apr 8, 2026
Updated
Apr 8, 2026
Vendor
Mervin Praison
Product
PraisonAI
Classifications
CWE-502, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 8, 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=< 4.5.115

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mervin Praison · PraisonAIversion=< 4.5.115

Published CVSS scores

9.8GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
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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