# CVE-2026-42073: Gitlawb OpenClaude CSRF and Denial of Service in MCP authentication

Source: https://junglewise.ai/threats/cve-2026-42073-gitlawb-openclaude-csrf-and-denial-of-service-in-mcp  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-02. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2026-42073 · Severity: medium · CVSS 6.5 · Published 2026-06-02

A vulnerability in the OpenClaude authentication process allows an attacker to disrupt a user's login session. By sending a specially crafted web request, an attacker can force the local authentication server to shut down prematurely. This results in a denial of service for the user attempting to log in, preventing them from completing the authentication flow.

Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-42073 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-42073 being exploited in the wild.

**How severe is CVE-2026-42073?** Medium severity, with a CVSS score of 6.5, published 2 June 2026.

**Which products and versions are affected?** @gitlawb/openclaude (npm) < 0.5.1, SEMVER:introduced=0,fixed=0.5.1.

**Is there a fix for CVE-2026-42073?** Yes. @gitlawb/openclaude (npm): upgrade to 0.5.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-42073 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-42073?** Check whether you run @gitlawb/openclaude (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- @gitlawb/openclaude (npm): upgrade to 0.5.1 or later

  ```sh
  npm install @gitlawb/openclaude@0.5.1
  ```


## Technical details

A logic flaw in the OAuth callback handler of OpenClaude MCP allows for a CSRF state check bypass. The application uses a conditional check that only validates the 'state' parameter if an 'error' parameter is absent. By providing any value in the 'error' query parameter, an attacker can bypass the state validation entirely. This triggers the error-handling block which calls a cleanup function, shutting down the local HTTP callback server and terminating the authentication session. This can be exploited remotely via cross-origin requests without knowledge of the valid state token. The issue is fixed in version 0.5.1 by decoupling the state validation from the error check.

## Affected products

- Gitlawb openclaude < 0.5.1

## Identifiers

- CVE-2026-42073
- GHSA-c73c-x77g-854r

## Timeline

- 2026-05-12: advisory: GitHub Advisory published
- 2026-05-12: patched: Fix released in version 0.5.1

## References

- [https://api.github.com/users/xancyber](https://api.github.com/users/xancyber)
- [https://github.com/xancyber](https://github.com/xancyber)
- [https://api.github.com/users/xancyber/gists%7B/gist_id%7D](https://api.github.com/users/xancyber/gists%7B/gist_id%7D)
- [https://api.github.com/users/xancyber/repos](https://api.github.com/users/xancyber/repos)
- [https://avatars.githubusercontent.com/u/272321005?v=4](https://avatars.githubusercontent.com/u/272321005?v=4)
- [https://api.github.com/users/xancyber/events%7B/privacy%7D](https://api.github.com/users/xancyber/events%7B/privacy%7D)

## Related threats

- [OpenClaude: Sandbox Bypass via Early-Exit Logic Flaw Allows Path Traversal](https://junglewise.ai/threats/cve-2026-35570-openclaude-sandbox-bypass-via-early-exit-logic-flaw-allows-path)