CVE-2026-44041

MEDIUM

UltraVNC vncWc2Mb calls wcslen() before validating that the wide string is NUL-terminated

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-44041. PoCs published by HermesNA-1.

AI-analyzed exploit summary This repository contains an auto-generated stub module for CVE-2026-44041, an out-of-bounds read vulnerability in UltraVNC through 1.8.2.2. The code includes metadata and a placeholder `run()` method that explicitly states it needs actual PoC implementation, with no functional exploit logic present.

Description

UltraVNC through 1.8.2.2 contains an out-of-bounds read in the wide-string to multibyte conversion helper. In rfb/dh.cpp:204, the vncWc2Mb() function passes a caller-supplied WCHAR pointer to wcslen() before any bounds check. If the caller provides a wide-character buffer that is not properly NUL-terminated, wcslen() reads past the end of the buffer until it encounters a NUL wchar, resulting in an out-of-bounds read. Under typical Win32 API usage this requires an abnormal caller contract. Impact is limited to a potential information disclosure from adjacent memory regions or a process crash (denial of service) if the over-read crosses a page boundary.

Exploits (1)

github STUB 1 stars
by HermesNA-1 · pythonpoc
https://github.com/HermesNA-1/SnakeSploit/tree/main/data/modules_generated/cve-2026-44041_ultravnc_through_1822.py

This repository contains an auto-generated stub module for CVE-2026-44041, an out-of-bounds read vulnerability in UltraVNC through 1.8.2.2. The code includes metadata and a placeholder `run()` method that explicitly states it needs actual PoC implementation, with no functional exploit logic present.

Classification
Stub 98%
Attack Type
Info Leak
Complexity
Moderate
Reliability
Theoretical
Target: UltraVNC through 1.8.2.2
No auth needed
Prerequisites: Network access to UltraVNC server (default port 5900) · Target running vulnerable UltraVNC version (<= 1.8.2.2)
mistral-large-3 · analyzed Jul 09, 2026 Full analysis →

References (3)

Core 3
Core References
Vendor Advisory vendor-advisory
UltraVNC project page
https://uvnc.com/
Product product
UltraVNC source repository
https://github.com/ultravnc/UltraVNC

Scores

CVSS v3 4.3
EPSS 0.0032
EPSS Percentile 24.0%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-125
Status published
Products (2)
uvnc/UltraVNC < 1.8.2.2
uvnc/ultravnc < 1.8.2.2
Published Jul 01, 2026
Tracked Since Jul 01, 2026