Integer Overflow or Wraparound Affecting ultravnc/UltraVNC package, versions [0,]
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-UNMANAGED-ULTRAVNCULTRAVNC-17747010
- published1 Jul 2026
- disclosed1 Jul 2026
- creditUnknown
Introduced: 1 Jul 2026
CVE-2026-7838 (opens in a new tab)How to fix?
There is no fixed version for ultravnc/UltraVNC.
Overview
Affected versions of this package are vulnerable to Integer Overflow or Wraparound via the reasonLen field in the RFB protocol failure-response parsing process. An attacker can achieve remote code execution by sending a specially crafted message from a malicious VNC server or a man-in-the-middle, causing a heap buffer overflow when the victim viewer connects. This is only exploitable if the attacker controls the VNC server or can intercept and modify the RFB stream.