CVE-2026-7839

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-01. a secondary CVSS source baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.1Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
56(Track)
EG Risk 56/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity91% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
50%
KEV
Not listed

Published

July 1, 2026

Last Modified

July 9, 2026

Advisory Details (3)

Auto-updated Sep 16, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

CVE-2026-7839: Hardcoded Default Admin Password | Securin

https://www.securin.io/zero-days/cve-2026-7839-hardcoded-default-admin-password-adminadmi2-ultravnc-repeater
generic

Home - UltraVNC VNC OFFICIAL SITE, Remote Desktop Free Opensource

https://uvnc.com/
generic

GitHub - ultravnc/UltraVNC: 👁️ UltraVNC Server, UltraVNC Viewer, UltraVNC Repeater and UltraVNC SC | Official repository: https://github.com/ultravnc/UltraVNC · GitHub

https://github.com/ultravnc/UltraVNC

Vendor Advisories for CVE-2026-7839(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 72× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 406 total refreshes for this CVE.

  1. 2026-09-20 20:16 UTCEPSS rescore
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-18 10:51 UTCGHSA enrichment
  4. 2026-09-18 06:37 UTCEG score recompute
  5. 2026-09-18 06:37 UTCGHSA enrichment
  6. 2026-09-16 14:08 UTCEPSS rescore
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-15 03:12 UTCEPSS rescore
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-14 08:30 UTCGHSA enrichment
  11. 2026-09-14 04:27 UTCGHSA enrichment
  12. 2026-09-14 00:28 UTCEG score recompute
  13. 2026-09-14 00:28 UTCGHSA enrichment
  14. 2026-09-13 13:09 UTCGHSA enrichment
  15. 2026-09-13 09:10 UTCEG score recompute
  16. 2026-09-13 09:10 UTCGHSA enrichment
  17. 2026-09-12 14:51 UTCEG score recompute
  18. 2026-09-12 14:51 UTCGHSA enrichment
  19. 2026-09-11 14:53 UTCEPSS rescore
  20. 2026-09-11 14:53 UTCEPSS rescore
  21. 2026-09-08 22:01 UTCEPSS rescore
  22. 2026-09-06 14:28 UTCEG score recompute
  23. 2026-09-06 14:28 UTCGHSA enrichment
  24. 2026-09-06 13:48 UTCEPSS rescore
  25. 2026-09-06 02:57 UTCEG score recompute
Show 75 more
  1. 2026-09-06 02:57 UTCGHSA enrichment
  2. 2026-09-04 05:07 UTCEPSS rescore
  3. 2026-09-02 14:12 UTCEPSS rescore
  4. 2026-09-01 13:54 UTCEPSS rescore
  5. 2026-09-01 04:40 UTCEPSS rescore
  6. 2026-09-01 04:40 UTCEPSS rescore
  7. 2026-08-31 01:20 UTCGHSA enrichment
  8. 2026-08-30 21:18 UTCEG score recompute
  9. 2026-08-30 21:18 UTCGHSA enrichment
  10. 2026-08-30 19:18 UTCEPSS rescore
  11. 2026-08-30 19:17 UTCEPSS rescore
  12. 2026-08-30 17:18 UTCGHSA enrichment
  13. 2026-08-30 13:18 UTCEG score recompute
  14. 2026-08-30 13:18 UTCGHSA enrichment
  15. 2026-08-30 01:22 UTCEPSS rescore
  16. 2026-08-28 21:42 UTCEPSS rescore
  17. 2026-08-28 02:48 UTCGHSA enrichment
  18. 2026-08-27 22:29 UTCEG score recompute
  19. 2026-08-27 22:29 UTCGHSA enrichment
  20. 2026-08-27 14:25 UTCEPSS rescore
  21. 2026-08-26 14:47 UTCEPSS rescore
  22. 2026-08-25 13:49 UTCEPSS rescore
  23. 2026-08-25 05:03 UTCGHSA enrichment
  24. 2026-08-25 01:03 UTCGHSA enrichment
  25. 2026-08-24 21:03 UTCGHSA enrichment
  26. 2026-08-24 15:00 UTCEG score recompute
  27. 2026-08-24 15:00 UTCGHSA enrichment
  28. 2026-08-24 14:18 UTCEPSS rescore
  29. 2026-08-24 10:58 UTCEG score recompute
  30. 2026-08-24 10:58 UTCGHSA enrichment
  31. 2026-08-24 04:52 UTCGHSA enrichment
  32. 2026-08-24 00:49 UTCGHSA enrichment
  33. 2026-08-23 20:50 UTCGHSA enrichment
  34. 2026-08-23 16:49 UTCGHSA enrichment
  35. 2026-08-23 12:49 UTCGHSA enrichment
  36. 2026-08-23 08:49 UTCGHSA enrichment
  37. 2026-08-23 04:40 UTCGHSA enrichment
  38. 2026-08-23 00:40 UTCEG score recompute
  39. 2026-08-23 00:40 UTCGHSA enrichment
  40. 2026-08-23 00:19 UTCEPSS rescore
  41. 2026-08-22 20:08 UTCGHSA enrichment
  42. 2026-08-22 15:29 UTCGHSA enrichment
  43. 2026-08-22 11:27 UTCGHSA enrichment
  44. 2026-08-22 07:27 UTCGHSA enrichment
  45. 2026-08-22 01:17 UTCEG score recompute
  46. 2026-08-22 01:17 UTCGHSA enrichment
  47. 2026-08-21 23:49 UTCEPSS rescore
  48. 2026-08-21 21:17 UTCGHSA enrichment
  49. 2026-08-21 17:18 UTCGHSA enrichment
  50. 2026-08-21 12:42 UTCGHSA enrichment
  51. 2026-08-21 08:41 UTCGHSA enrichment
  52. 2026-08-21 04:41 UTCGHSA enrichment
  53. 2026-08-20 23:56 UTCEG score recompute
  54. 2026-08-20 23:56 UTCGHSA enrichment
  55. 2026-08-20 22:56 UTCEPSS rescore
  56. 2026-08-20 19:57 UTCGHSA enrichment
  57. 2026-08-20 15:54 UTCGHSA enrichment
  58. 2026-08-20 08:49 UTCGHSA enrichment
  59. 2026-08-20 04:50 UTCEG score recompute
  60. 2026-08-20 04:50 UTCGHSA enrichment
  61. 2026-08-19 17:04 UTCEPSS rescore
  62. 2026-08-19 14:41 UTCGHSA enrichment
  63. 2026-08-19 10:19 UTCGHSA enrichment
  64. 2026-08-19 05:34 UTCGHSA enrichment
  65. 2026-08-19 01:01 UTCGHSA enrichment
  66. 2026-08-18 21:02 UTCEG score recompute
  67. 2026-08-18 21:02 UTCGHSA enrichment
  68. 2026-08-18 13:49 UTCEPSS rescore
  69. 2026-08-18 13:49 UTCEPSS rescore
  70. 2026-08-18 04:53 UTCGHSA enrichment
  71. 2026-08-17 23:37 UTCGHSA enrichment
  72. 2026-08-17 15:58 UTCEG score recompute
  73. 2026-08-17 15:58 UTCGHSA enrichment
  74. 2026-08-17 13:47 UTCEPSS rescore
  75. 2026-08-17 11:58 UTCGHSA enrichment

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-7839?
CVE-2026-7839 is a critical vulnerability published on July 1, 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 strcpys(savedpassword, 64,…
When was CVE-2026-7839 disclosed?
CVE-2026-7839 was first published in the National Vulnerability Database on July 1, 2026, with the most recent update on July 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-7839 actively exploited?
CVE-2026-7839 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 50.1% of all scored CVEs.
What is the CVSS score of CVE-2026-7839?
CVE-2026-7839 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-7839?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-7839, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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