# CVE-2026-44041: UltraVNC out-of-bounds read in vncWc2Mb conversion helper

Source: https://junglewise.ai/threats/cve-2026-44041-ultravnc-out-of-bounds-read-in-vncwc2mb-conversion-helper  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-01. Updated: 2026-07-01  
License: CC BY 4.0 with a link back

CVE-2026-44041 · Severity: medium · CVSS 4.3 · Published 2026-07-01

UltraVNC is a remote desktop tool used to control computers over a network. A security flaw in how the software handles certain text conversions could allow an attacker to crash the application or potentially view small amounts of private information from the computer's memory. This could disrupt remote support operations or lead to limited data exposure.

Technologies: [UltraVNC](https://junglewise.ai/threats/technologies/ultravnc). Vendors: [UltraVNC](https://junglewise.ai/threats/vendors/ultravnc).

## Quick answers

**Is CVE-2026-44041 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44041 being exploited in the wild.

**How severe is CVE-2026-44041?** Medium severity, with a CVSS score of 4.3, published 1 July 2026.

**Which products and versions are affected?** UltraVNC through 1.8.2.2.

**Is there a fix for CVE-2026-44041?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-44041 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-44041?** Check whether you run UltraVNC at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds read vulnerability exists in UltraVNC versions up to 1.8.2.2 within the vncWc2Mb() function in rfb/dh.cpp. The root cause is the function passing a caller-supplied WCHAR pointer to wcslen() before performing any bounds checking. If an attacker provides a wide-character buffer that lacks proper NUL-termination, wcslen() will read past the buffer's end until it encounters a NUL wchar. This can result in an information disclosure of adjacent memory or a process crash (DoS) if the read operation crosses a memory page boundary. While the vendor has released version 1.8.2.4, users should verify if this specific issue is addressed in the latest release.

## Affected products

- UltraVNC UltraVNC through 1.8.2.2

## Timeline

- 2026-07-01: advisory: Vulnerability published in NVD

## References

- [https://github.com/ultravnc/UltraVNC](https://github.com/ultravnc/UltraVNC)
- [https://uvnc.com/](https://uvnc.com/)

## Related threats

- [UltraVNC viewer heap buffer overflow in RFB failure-response parsing](https://junglewise.ai/threats/cve-2026-7838-ultravnc-viewer-heap-buffer-overflow-in-rfb-failure-response)
- [UltraVNC weak cryptography in MS-Logon II authentication](https://junglewise.ai/threats/cve-2026-7830-ultravnc-weak-cryptography-in-ms-logon-ii-authentication)
- [UltraVNC weak PRNG in VNC authentication challenge](https://junglewise.ai/threats/cve-2026-44040-ultravnc-weak-prng-in-vnc-authentication-challenge)