Out-of-bounds Read in Uvnc Ultravnc
CVE-2026-44041
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.004 (33.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 33rd percentile — 33.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Uvnc Ultravnc — versions 0
Weakness classification (CWE)
References
- 33c584b5-0579-4c06-b2a0-8d8329fcab9c (Product, vendor-advisory, Release Notes)
- 33c584b5-0579-4c06-b2a0-8d8329fcab9c (Product, product)
- 33c584b5-0579-4c06-b2a0-8d8329fcab9c
Frequently asked questions
- What is CVE-2026-44041?
- CVE-2026-44041 is a medium-severity vulnerability in Uvnc Ultravnc, classified under Out-of-bounds Read. CVSS score: 4.3/10. Published 2026-07-01.
- How severe is CVE-2026-44041?
- Medium severity. CVSS v3 base score is 4.3 out of 10.