# CVE-2008-3656: Denial of service in n/a

> Remote attackers can cause denial of service via CPU exhaustion in Ruby's WEBrick library using crafted HTTP requests.

- **Severity:** High 7.8 (`AV:N/AC:L/Au:N/C:N/I:N/A:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Aug 2008
- **Updated:** 7 Aug 2024
- **Also known as:** GHSA-823x-6r7f-v9x6

## What is CVE-2008-3656?

CVE-2008-3656 is a high-severity denial of service vulnerability in Ruby-Lang Ruby, published on 13 Aug 2008. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Algorithmic complexity vulnerability in the WEBrick::HTTPUtils.split_header_value function in WEBrick::HTTP::DefaultFileHandler in WEBrick in Ruby 1.8.5 and earlier, 1.8.6 through 1.8.6-p286, 1.8.7 through 1.8.7-p71, and 1.9 through r18423 allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted HTTP request that is processed by a backtracking regular expression.

Weakness: CWE-399

## Which versions are affected by CVE-2008-3656?

It affects 1 product.


Products: Ruby-Lang Ruby.

## How do I fix CVE-2008-3656?

Upgrade to a fixed version.

## Is CVE-2008-3656 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2008-3656 exists.

Public exploit code:

- Ruby WEBrick::HTTP::DefaultFileHandler DoS (metasploit)
- Ruby 1.9 - 'WEBrick::HTTP::DefaultFileHandler' Crafted HTTP Request Denial of Service (exploitdb)

## Other vulnerabilities in Ruby-Lang Ruby

- [CVE-2009-4124](https://insights.sbomify.com/CVE-2009-4124/): Memory corruption in n/a (critical 10.0)
- [CVE-2022-28738](https://insights.sbomify.com/CVE-2022-28738/): Use after free in n/a (critical 9.8)
- [CVE-2011-4121](https://insights.sbomify.com/CVE-2011-4121/): Weak cryptography in OpenSSL extension of Ruby (Git trunk) (critical 9.8)
- [CVE-2017-17790](https://insights.sbomify.com/CVE-2017-17790/): Command injection in n/a (critical 9.8)
- [CVE-2017-11465](https://insights.sbomify.com/CVE-2017-11465/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2008-3656 and fix it if it is affected.

What it is: CVE-2008-3656 is a high-severity denial of service vulnerability in Ruby-Lang Ruby, published on 13 Aug 2008. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2008-3656 exists.

Affected product: Ruby-Lang Ruby. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2008-3656/ (Markdown: https://insights.sbomify.com/CVE-2008-3656/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2008-3656
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2008-3656
- OSV: https://osv.dev/vulnerability/CVE-2008-3656

---
From sbomify Insights: https://insights.sbomify.com/CVE-2008-3656/
Summaries are generated and may contain mistakes; the official description above is the record.