CVE-2026-42073 OpenClaude's MCP OAuth Callback: State Check Bypass via error Param Leads to DoS
Attackers can bypass OAuth state validation in OpenClaude CLI to force a denial of service by shutting down the local authentication server.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-42073?
CVE-2026-42073 is a medium-severity vulnerability in Gitlawb openclaude, published on 2 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
OpenClaude is an open-source coding-agent command line interface for cloud and local model providers. Prior to version 0.5.1, the OpenClaude MCP authentication flow starts a temporary local HTTP server to handle OAuth callbacks. To prevent CSRF attacks, the server validates a state parameter against an internally stored value. However, due to a logic flaw in the order of conditionals, an attacker can completely bypass this check and force the server to shut down — without knowing the state value at all. This issue has been patched in version 0.5.1.
Which versions are affected by CVE-2026-42073?
2 open source packages ship an affected version, including @gitlawb/openclaude. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
@gitlawb/openclaude npm | All versions | 0.5.1 |
@gitlawb/openclaude npm | All versions | 0.5.1 |
Products include Gitlawb Openclaude.
How do I fix CVE-2026-42073?
Upgrade @gitlawb/openclaude to 0.5.1 or later.
Is CVE-2026-42073 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42073 exists.
Other vulnerabilities in Gitlawb openclaude
Sources
Also known as GHSA-c73c-x77g-854r.