# CVE-1999-0063: Denial of service in n/a

> Remote attackers can crash Cisco IOS devices by sending malicious UDP packets to the syslog port, causing a denial of service.

- **Severity:** Medium 5.0 (`AV:N/AC:L/Au:N/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:** No
- **Published:** 29 Sep 1999
- **Updated:** 1 Aug 2024
- **Also known as:** GHSA-h9f6-v64j-cw96

## What is CVE-1999-0063?

CVE-1999-0063 is a medium-severity denial of service vulnerability in Cisco Ios, published on 29 Sep 1999. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Cisco IOS 12.0 and other versions can be crashed by malicious UDP packets to the syslog port.

## Which versions are affected by CVE-1999-0063?

It affects 1 product.


Products: Cisco Ios.

## How do I fix CVE-1999-0063?

No fix has been published for CVE-1999-0063 yet. Limit exposure of the affected software until one is available.

## Is CVE-1999-0063 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-1999-0063 exists.

Public exploit code:

- Cisco IOS 12.0.2 - Syslog Crash (exploitdb)

## Other vulnerabilities in Cisco Ios

- [CVE-2017-12240](https://insights.sbomify.com/CVE-2017-12240/): Cisco IOS and IOS XE Software DHCP Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2017-3881](https://insights.sbomify.com/CVE-2017-3881/): Cisco IOS and IOS XE Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2018-0167](https://insights.sbomify.com/CVE-2018-0167/): Cisco IOS, XR, and XE Software Buffer Overflow (high 8.8, exploited in the wild)
- [CVE-2017-6736](https://insights.sbomify.com/CVE-2017-6736/): Cisco IOS and IOS XE Software SNMP Remote Code Execution (high 8.8, exploited in the wild)
- [CVE-2017-6737](https://insights.sbomify.com/CVE-2017-6737/): Cisco IOS and IOS XE Software SNMP Remote Code Execution (high 8.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-1999-0063 and fix it if it is affected.

What it is: CVE-1999-0063 is a medium-severity denial of service vulnerability in Cisco Ios, published on 29 Sep 1999. 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-1999-0063 exists.

Affected product: Cisco Ios. 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-1999-0063/ (Markdown: https://insights.sbomify.com/CVE-1999-0063/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-1999-0063
- NVD: https://nvd.nist.gov/vuln/detail/CVE-1999-0063
- OSV: https://osv.dev/vulnerability/CVE-1999-0063

---
From sbomify Insights: https://insights.sbomify.com/CVE-1999-0063/
Summaries are generated and may contain mistakes; the official description above is the record.