# CVE-2009-0362: Denial of service in n/a

> Remote attackers can cause denial of service in Fail2ban by sending crafted DNS names that trigger forced authentication failures due to a regex flaw.

- **Severity:** Medium 4.0 (`AV:N/AC:L/Au:S/C:N/I:N/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:** 13 Feb 2009
- **Updated:** 16 Sep 2024
- **Also known as:** DEBIAN-CVE-2009-0362, GHSA-rc77-w9xr-6vvf

## What is CVE-2009-0362?

CVE-2009-0362 is a medium-severity denial of service vulnerability in n/a, published on 13 Feb 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

filter.d/wuftpd.conf in Fail2ban 0.8.3 uses an incorrect regular expression that allows remote attackers to cause a denial of service (forced authentication failures) via a crafted reverse-resolved DNS name (rhost) entry that contains a substring that is interpreted as an IP address, a different vulnerability than CVE-2007-4321.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2009-0362?

It affects 1 product.


Products: Fail2ban Fail2ban.

## How do I fix CVE-2009-0362?

Upgrade to a fixed version.

## Is CVE-2009-0362 being exploited?

There is no known exploitation of CVE-2009-0362 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2012-5642](https://insights.sbomify.com/CVE-2012-5642/): Command injection in n/a (high 7.5)
- [CVE-2007-4321](https://insights.sbomify.com/CVE-2007-4321/): Denial of service in n/a (medium 6.8)
- [CVE-2021-32749](https://insights.sbomify.com/CVE-2021-32749/): Possible RCE vulnerability in mailing action using mailutils (mail-whois) (medium 6.1)
- [CVE-2013-7176](https://insights.sbomify.com/CVE-2013-7176/): Denial of service in n/a (medium 5.0)
- [CVE-2013-7177](https://insights.sbomify.com/CVE-2013-7177/): Denial of service in n/a (medium 5.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2009-0362 and fix it if it is affected.

What it is: CVE-2009-0362 is a medium-severity denial of service vulnerability in n/a, published on 13 Feb 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-2009-0362 in the wild and no public exploit code.

Affected product: n/a. 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-2009-0362/ (Markdown: https://insights.sbomify.com/CVE-2009-0362/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2009-0362
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2009-0362
- OSV: https://osv.dev/vulnerability/CVE-2009-0362

---
From sbomify Insights: https://insights.sbomify.com/CVE-2009-0362/
Summaries are generated and may contain mistakes; the official description above is the record.