# CVE-2009-3727: Information disclosure in n/a

> Remote attackers can enumerate valid SIP usernames by analyzing error message differences in Asterisk PBX systems.

- **Severity:** Medium 5.0 (`AV:N/AC:L/Au:N/C:P/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Nov 2009
- **Updated:** 7 Aug 2024
- **Also known as:** DEBIAN-CVE-2009-3727, GHSA-827c-j6w2-8fg4

## What is CVE-2009-3727?

CVE-2009-3727 is a medium-severity vulnerability in Digium Asterisk, published on 10 Nov 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Asterisk Open Source 1.2.x before 1.2.35, 1.4.x before 1.4.26.3, 1.6.0.x before 1.6.0.17, and 1.6.1.x before 1.6.1.9; Business Edition A.x.x, B.x.x before B.2.5.12, C.2.x.x before C.2.4.5, and C.3.x.x before C.3.2.2; AsteriskNOW 1.5; and s800i 1.3.x before 1.3.0.5 generate different error messages depending on whether a SIP username is valid, which allows remote attackers to enumerate valid usernames via multiple crafted REGISTER messages with inconsistent usernames in the URI in the To header and the Digest in the Authorization header.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2009-3727?

It affects 3 products.


Products: Digium Asterisk, Digium Asterisknow, Digium S800i.

## How do I fix CVE-2009-3727?

Upgrade to a fixed version.

## Is CVE-2009-3727 being exploited?

There is no known exploitation of CVE-2009-3727 in the wild and no public exploit code.

## Other vulnerabilities in Digium Asterisk

- [CVE-2017-14100](https://insights.sbomify.com/CVE-2017-14100/): Command injection in n/a (critical 9.8)
- [CVE-2014-8418](https://insights.sbomify.com/CVE-2014-8418/): Privilege escalation in n/a (critical 9.0)
- [CVE-2011-1599](https://insights.sbomify.com/CVE-2011-1599/): Missing authorization in n/a (critical 9.0)
- [CVE-2017-16671](https://insights.sbomify.com/CVE-2017-16671/): Memory corruption in n/a (high 8.8)
- [CVE-2017-7617](https://insights.sbomify.com/CVE-2017-7617/): Memory corruption in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2009-3727 and fix it if it is affected.

What it is: CVE-2009-3727 is a medium-severity vulnerability in Digium Asterisk, published on 10 Nov 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-2009-3727 in the wild and no public exploit code.

Affected product: Digium Asterisk. 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-2009-3727/ (Markdown: https://insights.sbomify.com/CVE-2009-3727/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2009-3727
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2009-3727
- OSV: https://osv.dev/vulnerability/CVE-2009-3727

---
From sbomify Insights: https://insights.sbomify.com/CVE-2009-3727/
Summaries are generated and may contain mistakes; the official description above is the record.