TI-2026-30441 Aliases CVE-2026-42073 GHSA-c73c-x77g-854r

OpenClaude's MCP OAuth Callback: State Check Bypass via error Param Leads to DoS

MEDIUM 62CWE-352Published 2026-06-02 · Updated 2026-06-02

Key facts

Attack vector: Network
Privileges required: None
User interaction: Required
Attack complexity: Low
Impact type: Tampering, Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-352 and CWE-400.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00255 17th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed openclaude (Gitlawb): 0.5.1@gitlawb/openclaude (npm): 0.5.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Gitlawb	openclaude	before 0.5.1	0.5.1	Patch available	CNA
—	@gitlawb/openclaude (npm)	before 0.5.1	0.5.1	Patch available	GHSA-c73c-x77g-854r

openclaude VendorGitlawb Affected before 0.5.1 Fixed in 0.5.1 Patch available CNA
@gitlawb/openclaude (npm) Vendor— Affected before 0.5.1 Fixed in 0.5.1 Patch available GHSA-c73c-x77g-854r

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:gitlawb:openclaude::::::::	before 0.5.1	Vulnerable	Gitlawb

cpe:2.3:a:gitlawb:openclaude:*:*:*:*:*:*:*:* Versions before 0.5.1 Vulnerable ·Gitlawb

Remediation

Fix · CNA openclaude (Gitlawb) Fixed in 0.5.1
Fix · GHSA-c73c-x77g-854r @gitlawb/openclaude (npm) Fixed in 0.5.1 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-42073
2026-10-03 Alias added: GHSA-c73c-x77g-854r

References

Other 2

TI-2026-30442 OpenClaude: Sandbox Bypass via Model-Controlled `dangerouslyDisableSandbox` Input CVSS 4.0CRITICAL 9.3
TI-2026-27674 OpenClaude has Sandbox Bypass via Early-Exit Logic Flaw that Allows Path Traversal CVSS 3.1HIGH 8.4

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences