PraisonAI has an origin validation bypass in MCP HTTP Stream transport that allows browser-mediated unauthenticated tool execution on local MCP server

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N

EPSS

• CVE-2026-55529: 0.18% estimated exploitation activity in the next 30 days; percentile 7.01 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary PraisonAI's MCP HTTP Stream transport uses an unsafe prefix match when validating the Origin header. The default localhost allowlist includes origins such as http://localhost, and the validation accepts any origin that starts with an allowed value. As a result, an attacker-controlled origin such as http://localhost.evil.example passes the localhost origin check. When the MCP HTTP Stream server is started without an API key, which is the CLI default, this allows a malicious webpage to trigger unauthenticated MCP tools/call requests against a locally running PraisonAI MCP server. This is best framed as a browser-mediated localhost attack / DNS-rebinding-style Origin validation bypass. The default server binds to 127.0.0.1, so this is not a directly internet-facing unauthenticated API in the default configuration. Details Relevant source locations: - src/praisonai/praisonai/mcpserver/cli.py - src/praisonai/praisonai/mcpserver/transports/httpstream.py -…

Published by the source

25 Aug 2026, 14:26 UTC

Last modified by the source

25 Aug 2026, 14:26 UTC

Source last checked

26 Oct 2026, 13:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-wj6g-v78p-6fx3

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# Patch Next advisory brief: CVE-2026-55529

Advisory: PraisonAI has an origin validation bypass in MCP HTTP Stream transport that allows browser-mediated unauthenticated tool execution on local MCP server
IDs: CVE-2026-55529, GHSA-wj6g-v78p-6fx3
Record: https://patchnext.com/advisories/cve-2026-55529 (revision 1, source checked 26 Oct 2026, 13:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: praisonai 4.6.58. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI praisonai: affected < 4.6.58; fixed in 4.6.58

## Suggested inspection (read-only)
- `python -m pip show praisonai`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on praisonai.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-wj6g-v78p-6fx3 (GitHub-reviewed advisory GHSA-wj6g-v78p-6fx3 lists affected ranges: PyPI praisonai >=0 <4.6.58)

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