CVE-2026-7839

Critical · CVSS 9.1

UltraVNC Repeater — Hardcoded Default Credentials (CWE-798)

CVSS: 9.1; nvd
EPSS: —
KEV: No
Class: other; CWE-798

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.

Search profile — drives PoC discovery

Symbols settings2.txtadminadmi2strcpy_s(saved_password, 64, "adminadmi2")wi_decode_authsaved_passwordrepeater/webgui/settings.csettings.c:197

Keywords CVE-2026-7839UltraVNC repeater hardcoded passwordUltraVNC repeater default credentialsadminadmi2UltraVNC repeater HTTP adminwi_decode_authUltraVNC repeater 1.8.2.2settings2.txt hardcodedUltraVNC repeater PoCUltraVNC HTTP Basic-auth bypass

Versions: <= 1.8.2.2

References

Status: enriched · ingested 2026-07-02T18:00:43.000Z · profiled 2026-07-02T18:30:43.000Z