CVE-2026-7839
Published: 01 July 2026
Summary
CVE-2026-7839 is a critical-severity Use of Hard-coded Credentials (CWE-798) vulnerability in Uvnc Ultravnc. Its CVSS base score is 9.1 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Default Accounts (T1078.001); ranked at the 24.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-40885
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Hardcoded default admin password enables direct use of default credentials for remote auth.
CVEs Like This One
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Enables users to notice when hard-coded credentials have been exploited for unauthorized access.
Security training explicitly warns against hard-coded credentials, lowering their use in systems.
Policy and procedures prohibit hard-coded credentials in favor of managed authentication.
External identity providers eliminate the need for hard-coded credentials in applications.
Changing default authenticators prior to first use and protecting content prevents use of hard-coded credentials.
Central credential stores and rotation policies remove the need for hard-coded credentials in configuration files or code.
Intelligence programs surface reports of campaigns that abuse hard-coded credentials in products, prompting removal or replacement and thereby reducing successful exploitation.
Planned investment enables secure credential storage and management systems instead of hard-coded credentials.