# CVE-2017-11173: Missing Regex anchor in Rack-Cors allows malicious third party site to perform CORS request

> A regex flaw in rack-cors allows malicious sites to bypass CORS restrictions, enabling unauthorized cross-origin requests if specific domain configurations are used.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 13 Jul 2017
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2017-11173, DSA-3931-1, GHSA-2j9c-9vmv-7m39, UBUNTU-CVE-2017-11173

## What is CVE-2017-11173?

CVE-2017-11173 is a high-severity vulnerability in Debian Debian Linux, published on 13 Jul 2017. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Missing anchor in generated regex for rack-cors before 0.4.1 allows a malicious third-party site to perform CORS requests. If the configuration were intended to allow only the trusted example.com domain name and not the malicious example.net domain name, then example.com.example.net (as well as example.com-example.net) would be inadvertently allowed.

## Which versions are affected by CVE-2017-11173?

2 open source packages ship an affected version, including rack-cors. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rack-cors` | RubyGems | All versions | 0.4.1 |
| `rack-cors` | RubyGems | All versions | 0.4.1 |

Products: Debian Debian Linux, Rack-Cors Project Rack-Cors.

## How do I fix CVE-2017-11173?

Upgrade rack-cors to 0.4.1 or later.

## Is CVE-2017-11173 being exploited?

There is no known exploitation of CVE-2017-11173 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-11173 and fix it if it is affected.

What it is: CVE-2017-11173 is a high-severity vulnerability in Debian Debian Linux, published on 13 Jul 2017. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2017-11173 in the wild and no public exploit code.

Affected packages and fixed versions:
- rack-cors (RubyGems): affected all versions; fixed in 0.4.1
- rack-cors (RubyGems): affected all versions; fixed in 0.4.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2017-11173/ (Markdown: https://insights.sbomify.com/CVE-2017-11173/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-11173
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-11173
- OSV: https://osv.dev/vulnerability/CVE-2017-11173

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-11173/
Summaries are generated and may contain mistakes; the official description above is the record.