Security Digest · Vulnerability record
CVE-2025-49596: MCP Inspector proxy server lacks authentication between the Inspector client and proxy
The MCP inspector is a developer tool for testing and debugging MCP servers.
CVSS 9.4 Critical EPSS 44.5% · p99 Check exposure
Should you act?
High exploit likelihood
EPSS ranks it in the top 5% of all CVEs for likely exploitation in the next 30 days. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 44.5%, percentile 99: FIRST’s model estimates a 44.5% chance of exploitation activity in the next 30 days, higher than 99% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Only applies if your dependency tree includes
@modelcontextprotocol/inspector(npm) < 0.14.1, fixed in 0.14.1. Check your lockfile, including transitive dependencies. - Editorial verdict: Check exposure. MCP Inspector: Unauthenticated RCE via Browser CSRF — Fixed since June 2025, but Inspector sits in project devDependencies and npx caches, so old copies survive; confirm 0.14.1+ and never run it with auth disabled.
What it is
The MCP inspector is a developer tool for testing and debugging MCP servers. Versions of MCP Inspector below 0.14.1 are vulnerable to remote code execution due to lack of authentication between the Inspector client and proxy, allowing unauthenticated requests to launch MCP commands over stdio. Users should immediately upgrade to version 0.14.1 or later to address these vulnerabilities.
From the GitHub advisory
Versions of MCP Inspector below 0.14.1 are vulnerable to remote code execution due to lack of authentication between the Inspector client and proxy, allowing unauthenticated requests to launch MCP commands over stdio. Users should immediately upgrade to version 0.14.1 or later to address these vulnerabilities.
Credit: Rémy Marot
Weakness type: CWE-306.
Product: @modelcontextprotocol/inspector (npm) · Assigned by: GitHub_M · Published: 2025-06-13
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | @modelcontextprotocol/inspector | < 0.14.1 | 0.14.1 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| modelcontextprotocol | inspector | < 0.14.1 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 4.0 | 9.4 Critical | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
| GitHub | 4.0 | 9.4 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: none
- Privileges required: none (no login)
- User interaction: passive
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable no, technical impact total.
- FIRST EPSS (model of 2026-10-21): 44.45% probability of exploitation activity in the next 30 days; percentile 99.
Timeline
- — CVE record published by GitHub_M
- — GitHub-reviewed advisory GHSA-7f8r-222p-6f5g published (critical)
- — erroneo.us brief: MCP Inspector: Unauthenticated RCE via Browser CSRF
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-7f8r-222p-6f5g github.com
- CVE.org record CVE-2025-49596 cve.org
- NVD entry CVE-2025-49596 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- thenewstack.io thenewstack.io
- oligo.security oligo.security