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Critical, CVSS 9.1amended

PraisonAI has a Browser Server WebSocket origin validation bypass via unanchored regex (patch bypass of CVE-2026-40289 / GHSA-8x8f-54wf-vv92)

CVE-2026-55536GHSA-6g6r-q6gw-w8fg

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (praisonai 4.6.58), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
9.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS
  • CVE-2026-55536: 0.52% estimated exploitation activity in the next 30 days; percentile 44.27 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary praisonai/browser/server.py validates incoming WebSocket connections using a Chrome extension Origin check. The regex chrome-extension://[a-z0-9]{32} is applied with re.match(), which only anchors at the start of the string, not the end. Any Origin header with more than 32 alphanumeric characters after chrome-extension:// — including non-alphanumeric trailing characters — passes the check. This is a patch bypass of GHSA-8x8f-54wf-vv92. That advisory triggered the addition of origin validation; this finding shows the validation is bypassable by any WebSocket client that forges an Origin header. After bypassing, the attacker can send startsession commands that are executed by any Chrome extension currently connected to the server — causing the extension to perform arbitrary browser automation including cookie theft and screenshot capture. Details Vulnerable code — browser/server.py line 186: re.match() returns a match object if the pattern matches at the beginning of the…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-6g6r-q6gw-w8fg

  2. Revision 2 · amended ·

    Amended from osv record GHSA-6g6r-q6gw-w8fg

  3. Revision 1 · created ·

    Published from ghsa record GHSA-6g6r-q6gw-w8fg

Agent brief

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# Patch Next advisory brief: CVE-2026-55536

Advisory: PraisonAI has a Browser Server WebSocket origin validation bypass via unanchored regex (patch bypass of CVE-2026-40289 / GHSA-8x8f-54wf-vv92)
IDs: CVE-2026-55536, GHSA-6g6r-q6gw-w8fg
Record: https://patchnext.com/advisories/cve-2026-55536 (revision 3, 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: Critical (CVSS 9.1)
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-6g6r-q6gw-w8fg (GitHub-reviewed advisory GHSA-6g6r-q6gw-w8fg lists affected ranges: PyPI praisonai >=0 <4.6.58)
- Verified: https://osv.dev/vulnerability/GHSA-6g6r-q6gw-w8fg (OSV record GHSA-6g6r-q6gw-w8fg lists affected ranges: PyPI praisonai >=0 <4.6.58 (fixed))

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