# CVE-2017-17850: Null dereference in n/a

> A missing contact header in SIP messages causes a null pointer dereference crash in Asterisk, leading to denial of service.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Dec 2017
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2017-17850, GHSA-cx4v-84p4-4vh6, UBUNTU-CVE-2017-17850

## What is CVE-2017-17850?

CVE-2017-17850 is a high-severity vulnerability in Digium Asterisk, published on 23 Dec 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in Asterisk 13.18.4 and older, 14.7.4 and older, 15.1.4 and older, and 13.18-cert1 and older. A select set of SIP messages create a dialog in Asterisk. Those SIP messages must contain a contact header. For those messages, if the header was not present and the PJSIP channel driver was used, Asterisk would crash. The severity of this vulnerability is somewhat mitigated if authentication is enabled. If authentication is enabled, a user would have to first be authorized before reaching the crash point.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2017-17850?

It affects 2 products.


Products: Digium Asterisk, Digium Certified Asterisk.

## How do I fix CVE-2017-17850?

Upgrade to a fixed version.

## Is CVE-2017-17850 being exploited?

There is no known exploitation of CVE-2017-17850 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-2017-17850 and fix it if it is affected.

What it is: CVE-2017-17850 is a high-severity vulnerability in Digium Asterisk, published on 23 Dec 2017. 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-2017-17850 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-2017-17850/ (Markdown: https://insights.sbomify.com/CVE-2017-17850/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-17850
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-17850
- OSV: https://osv.dev/vulnerability/CVE-2017-17850

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-17850/
Summaries are generated and may contain mistakes; the official description above is the record.