# CVE-2009-3287: High severity vulnerability that affects thin

> Attackers can spoof client IP addresses by manipulating the X-Forwarded-For header, bypassing IP-based access controls or logging mechanisms.

- **Severity:** High 7.5 (`AV:N/AC:L/Au:N/C:P/I:P/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Sep 2009
- **Updated:** 16 Sep 2024
- **Also known as:** DEBIAN-CVE-2009-3287, GHSA-j24p-r6wx-r79w

## What is CVE-2009-3287?

CVE-2009-3287 is a high-severity vulnerability in n/a, published on 22 Sep 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

lib/thin/connection.rb in Thin web server before 1.2.4 relies on the X-Forwarded-For header to determine the IP address of the client, which allows remote attackers to spoof the IP address and hide activities via a modified X-Forwarded-For header.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2009-3287?

2 open source packages ship an affected version, including thin. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `thin` | RubyGems | All versions | 1.2.4 |
| `thin` | RubyGems | All versions | 1.2.4 |

Products: Macournoyer Thin.

## How do I fix CVE-2009-3287?

Upgrade thin to 1.2.4 or later.

## Is CVE-2009-3287 being exploited?

There is no known exploitation of CVE-2009-3287 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2009-3287 and fix it if it is affected.

What it is: CVE-2009-3287 is a high-severity vulnerability in n/a, published on 22 Sep 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2009-3287 in the wild and no public exploit code.

Affected packages and fixed versions:
- thin (RubyGems): affected all versions; fixed in 1.2.4
- thin (RubyGems): affected all versions; fixed in 1.2.4

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-2009-3287/ (Markdown: https://insights.sbomify.com/CVE-2009-3287/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2009-3287
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2009-3287
- OSV: https://osv.dev/vulnerability/CVE-2009-3287

---
From sbomify Insights: https://insights.sbomify.com/CVE-2009-3287/
Summaries are generated and may contain mistakes; the official description above is the record.