---
title: "CVE-2026-39890: PraisonAI Vulnerable to Remote Code Execution via YAML Deserialization in Agent Definition Loading"
url: https://erroneo.us/security/cve/CVE-2026-39890/
description: "CVE-2026-39890 (praisonai (PyPI)): PraisonAI is a multi-agent teams system. Prior to 4.5.115, the AgentService.loadAgentFromFile method uses the js-yaml…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-04-08
date_modified: 2026-05-09
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-39890"
kev: false
cvss: 9.8
epss: 0.00812
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-39890: PraisonAI Vulnerable to Remote Code Execution via YAML Deserialization in Agent Definition Loading

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.8% , percentile 56: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 56% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes praisonai (PyPI) <= 4.5.114, fixed in 4.5.115 . Check your lockfile, including transitive dependencies.

## What it is

PraisonAI is a multi-agent teams system. Prior to 4.5.115, the AgentService.loadAgentFromFile method uses the js-yaml library to parse YAML files without disabling dangerous tags (such as !!js/function and !!js/undefined). This allows an attacker to craft a malicious YAML file that, when parsed, executes arbitrary JavaScript code. An attacker can exploit this vulnerability by uploading a malicious agent definition file via the API endpoint, leading to remote code execution (RCE) on the server. This vulnerability is fixed in 4.5.115.

## Affected packages

- PyPI `praisonai` <= 4.5.114 → fixed: 4.5.115

## Affected products (CVE record)

- MervinPraison PraisonAI: < 4.5.115

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.81% probability of exploitation activity in the next 30 days; percentile 56.

## Sources

- [GitHub Advisory GHSA-32vr-5gcf-3pw2](https://github.com/advisories/GHSA-32vr-5gcf-3pw2)
- [CVE.org record CVE-2026-39890](https://www.cve.org/CVERecord?id=CVE-2026-39890)
- [NVD entry CVE-2026-39890](https://nvd.nist.gov/vuln/detail/CVE-2026-39890)
- [github.com](https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-32vr-5gcf-3pw2)
- [github.com](https://github.com/MervinPraison/PraisonAI/releases/tag/v4.5.115)

---
Source page: https://erroneo.us/security/cve/CVE-2026-39890/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt