CVE-2026-7839
9.1 · CRITICALOverview
CVE-2026-7839 is a critical-severity vulnerability affecting uvnc ultravnc. It was published on July 1, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
UltraVNC repeater through 1.8.2.2 initializes the HTTP administration server with a hardcoded default password. In repeater/webgui/settings.c:197, when settings2.txt is absent on first run the repeater writes the literal string "adminadmi2" as the admin password via strcpy_s(saved_password, 64, "adminadmi2"). The HTTP Basic-auth handler wi_decode_auth() checks this password without rate-limiting or lockout. Any remote attacker who can reach the repeater HTTP port (default TCP 80) can authenticate as administrator using the well-known default credential on a fresh or unmodified installation, gaining full control of the repeater configuration including allow/deny rules and session visibility.
Remediation
Check the references section for vendor advisories and patches from uvnc. Update ultravnc to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| uvnc | ultravnc | 0 | Affected |
Frequently Asked Questions
What is CVE-2026-7839?
CVE-2026-7839 is a critical-severity vulnerability affecting uvnc ultravnc. It was published on July 1, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).
How severe is CVE-2026-7839?
This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-7839?
Check the references section for vendor advisories and patches from uvnc. Update ultravnc to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-7839?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-7839 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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