# CVE-2019-8263: Memory corruption in UltraVNC

> A stack-based buffer overflow in the UltraVNC client allows remote attackers to cause a denial of service via network connectivity.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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:** A user has to click or open something
- **Fix available:** No
- **Published:** 5 Mar 2019
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-3ccg-xj7w-w764

## What is CVE-2019-8263?

CVE-2019-8263 is a medium-severity memory corruption vulnerability in Kaspersky Lab UltraVNC, published on 5 Mar 2019. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

UltraVNC revision 1205 has stack-based buffer overflow vulnerability in VNC client code inside ShowConnInfo routine, which leads to a denial of service (DoS) condition. This attack appear to be exploitable via network connectivity. User interaction is required to trigger this vulnerability. This vulnerability has been fixed in revision 1206.

Weakness: CWE-787 (Out-of-bounds Write), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2019-8263?

It affects 4 products.


Products: Siemens Sinumerik Access Mymachine\/P2p, Siemens Sinumerik Pcu Base Win10 Software\/Ipc, Siemens Sinumerik Pcu Base Win7 Software\/Ipc, Uvnc Ultravnc.

## How do I fix CVE-2019-8263?

No fix has been published for CVE-2019-8263 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-8263 being exploited?

There is no known exploitation of CVE-2019-8263 in the wild and no public exploit code.

## Other vulnerabilities in Kaspersky Lab UltraVNC

- [CVE-2019-8268](https://insights.sbomify.com/CVE-2019-8268/): Memory corruption in UltraVNC (critical 9.8)
- [CVE-2019-8271](https://insights.sbomify.com/CVE-2019-8271/): Memory corruption in UltraVNC (critical 9.8)
- [CVE-2019-8272](https://insights.sbomify.com/CVE-2019-8272/): Integer overflow in UltraVNC (critical 9.8)
- [CVE-2019-8273](https://insights.sbomify.com/CVE-2019-8273/): Memory corruption in UltraVNC (critical 9.8)
- [CVE-2019-8274](https://insights.sbomify.com/CVE-2019-8274/): Memory corruption in UltraVNC (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-8263 and fix it if it is affected.

What it is: CVE-2019-8263 is a medium-severity memory corruption vulnerability in Kaspersky Lab UltraVNC, published on 5 Mar 2019. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2019-8263 in the wild and no public exploit code.

Affected product: Kaspersky Lab UltraVNC. 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-2019-8263/ (Markdown: https://insights.sbomify.com/CVE-2019-8263/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-8263
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-8263
- OSV: https://osv.dev/vulnerability/CVE-2019-8263

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-8263/
Summaries are generated and may contain mistakes; the official description above is the record.