# CVE-2018-16657: Null dereference in n/a

> A crafted SIP message with an invalid Via header causes a segmentation fault in Kamailio, leading to denial of service and potential arbitrary code execution.

- **Severity:** Critical 9.8 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 7 Sep 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-16657, DLA-1503-1, DSA-4292-1, GHSA-4477-4jr7-cfjq, UBUNTU-CVE-2018-16657

## What is CVE-2018-16657?

CVE-2018-16657 is a critical vulnerability in Debian Debian Linux, published on 7 Sep 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In Kamailio before 5.0.7 and 5.1.x before 5.1.4, a crafted SIP message with an invalid Via header causes a segmentation fault and crashes Kamailio. The reason is missing input validation in the crcitt_string_array core function for calculating a CRC hash for To tags. (An additional error is present in the check_via_address core function: this function also misses input validation.) This could result in denial of service and potentially the execution of arbitrary code.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2018-16657?

It affects 2 products.


Products: Debian Debian Linux, Kamailio Kamailio.

## How do I fix CVE-2018-16657?

Upgrade to a fixed version.

## Is CVE-2018-16657 being exploited?

There is no known exploitation of CVE-2018-16657 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-16657 and fix it if it is affected.

What it is: CVE-2018-16657 is a critical vulnerability in Debian Debian Linux, published on 7 Sep 2018. 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-2018-16657 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2018-16657/ (Markdown: https://insights.sbomify.com/CVE-2018-16657/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-16657
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-16657
- OSV: https://osv.dev/vulnerability/CVE-2018-16657

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-16657/
Summaries are generated and may contain mistakes; the official description above is the record.