# MCP Java SDK has a Hardcoded Wildcard CORS (Access-Control-Allow-Origin: \*)

Advisory record · `GHSA-hv2w-8mjj-jw22`

- **Identifiers:** `GHSA-hv2w-8mjj-jw22` · `CVE-2026-34237`
- **State:** Confirmed
- **Severity:** CVSS 6.1 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-942](https://cwe.mitre.org/data/definitions/942.html)
- **Tags:** [CWE-942](https://agentprime.io/advisories/tag/cwe-942.md)
- **Published:** 30 Mar 2026
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 30 Mar 2026, 17:26 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `io.modelcontextprotocol.sdk:mcp-core` (Maven): affected `>=1.0.0, <1.0.1 || >=1.1.0, <1.1.1 || <0.18.3`; fixed in `1.0.1`, `1.1.1`, `0.18.3`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.1 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0023, the 14th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:17 UTC: First seen by agentprime
- 31 Oct 2026, 14:17 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-hv2w-8mjj-jw22)

## Sources

- [GitHub Advisory Database: GHSA-hv2w-8mjj-jw22](https://github.com/advisories/GHSA-hv2w-8mjj-jw22)
- [OSV: GHSA-hv2w-8mjj-jw22](https://osv.dev/vulnerability/GHSA-hv2w-8mjj-jw22)
- <https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-34237>
- <https://cheatsheetseries.owasp.org/cheatsheets/HTTP_Headers_Cheat_Sheet.html#access-control-allow-origin>
- <https://github.com/modelcontextprotocol/java-sdk>
- <https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289>
- <https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-hv2w-8mjj-jw22>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-hv2w-8mjj-jw22/>. Everything for agents: <https://agentprime.io/llms.txt>.