claude-code-router CORS. misconfiguration

published 2025-08-21 14 mo ago modified 2026-06-17 4 mo ago also GHSA-8hmm-4crw-vm2c , EUVD-2025-25479

cvss: 0.0; version 3.1, GitHub
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 23%
public exploits: 0; none known

claude-code-router is a powerful tool to route Claude Code requests to different models and customize any request. Due to improper Cross-Origin Resource Sharing (CORS) configuration, there is a risk that user API Keys or equivalent credentials may be exposed to untrusted domains. Attackers could exploit this misconfiguration to steal credentials, abuse accounts, exhaust quotas, or access sensitive data. The issue has been patched in v1.0.34.

Patch / fix

fixed in 1

npm @musistudio/claude-code-router 1.0.34

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: total
Assessed: 14 mo ago (2025-08-21)

Exploit prediction

0.30% chance of exploitation in the next 30 days, higher than 23% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.1	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U
CNA	4.0	8.1	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
GitHub	3.1	0.0	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	@musistudio/claude-code-router	<1.0.34	1.0.34

Affected products

musistudio claude-code-router

Classification

Weakness

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
CWE-942 Permissive Cross-domain Security Policy with Untrusted Domains

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary