CVE-2026-7839 PUBLISHED

UltraVNC repeater ships hardcoded default admin password allowing unauthenticated admin access

Assigner: securin
Reserved: 05.05.2026 Published: 01.07.2026 Updated: 01.07.2026

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.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS Score: 9.1

Product Status

Vendor uvnc
Product UltraVNC
Versions Default: unaffected
  • affected from 0 to 1.8.2.2 (incl.)

Credits

  • Arjun Basnet, Securin (arjun.basnet@securin.io) finder

References

Problem Types

  • Use of Hard-coded Credentials CWE