# Missing Regex anchor in Rack-Cors allows malicious third party site to perform CORS request

Advisory record · `GHSA-2j9c-9vmv-7m39`

- **Identifiers:** `GHSA-2j9c-9vmv-7m39` · `CVE-2017-11173`
- **State:** Confirmed
- **Severity:** CVSS 8.8 High
- **Critical:** No
- **Published:** 31 Jul 2018
- **Updated:** 3 Dec 2024
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 31 Jul 2018, 18:18 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `rack-cors` (RubyGems): affected `<0.4.1`; fixed in `0.4.1`

## 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

- 8.8 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`, from GitHub Advisory Database

- **CISA KEV:** Not listed.
- **EPSS:** 0.023, the 83rd percentile, on 10 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the GitHub Advisory Database, published 31 Jul 2018. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-2j9c-9vmv-7m39](https://github.com/advisories/GHSA-2j9c-9vmv-7m39)
- [OSV: GHSA-2j9c-9vmv-7m39](https://osv.dev/vulnerability/GHSA-2j9c-9vmv-7m39)
- <https://nvd.nist.gov/vuln/detail/CVE-2017-11173>
- <https://github.com/cyu/rack-cors/commit/42ebe6caa8e85ffa9c8a171bda668ba1acc7a5e6>
- <https://github.com/cyu/rack-cors>
- <https://packetstormsecurity.com/files/143345/rack-cors-Missing-Anchor.html>
- <http://seclists.org/fulldisclosure/2017/Jul/22>
- <http://www.debian.org/security/2017/dsa-3931>

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-2j9c-9vmv-7m39>, 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-2j9c-9vmv-7m39/>. Everything for agents: <https://agentprime.io/llms.txt>.