CVE-2026-7830

HIGHPre-NVD 7.47.4—
EchelonGraph scoreMEDIUM confidence

Score 7.4 from GitHub Security Advisory (severity: HIGH) published 2026-07-01. a secondary CVSS source baseline 7.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
7.4EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.4Exploit: None knownExposed services: Not assessed

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

UltraVNC through 1.8.2.2 uses inadequate cryptography in the MS-Logon II authentication scheme (rfbUltraVNC_MsLogonIIAuth). In rfb/dh.cpp the Diffie-Hellman key exchange is performed with parameters that fit in an unsigned 64-bit integer (DH_MAX_BITS controls the prime size). A 64-bit DH key can be broken by Pollard's rho algorithm in under one second on current hardware. Additionally, the private exponent is generated by the rng() function, which multiplies three libc rand() values seeded from time(NULL). With approximately 31 bits of internal state and a time-based seed, the private exponent is recoverable in under a minute by a passive observer. A network attacker who can observe the MS-Logon II handshake (via sniffing, recording, or man-in-the-middle) can derive the shared DH key and decrypt the encapsulated username and password, resulting in full credential disclosure. This affects legacy MS-Logon II connections; MS-Logon III (X25519 + AES-256-GCM) is unaffected.

CVSS v3
7.4
EG Score
7.4HIGHmedium confidence
EG Risk
33
EG Risk 33/100

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
Severity74% × 45%
Exploitation0% × 40%
Automatability0% × 15%
EPSS PROB
0.3%
EPSS %ILE
19th
KEV
Not listed

Published

July 1, 2026

Last Modified

July 9, 2026

Advisory Details (2)

Auto-updated Jul 1, 2026
No fix on record yet.
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-2026-7830(1)

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

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 37× 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 250 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-7830?
CVE-2026-7830 is a high vulnerability published on July 1, 2026. UltraVNC through 1.8.2.2 uses inadequate cryptography in the MS-Logon II authentication scheme (rfbUltraVNCMsLogonIIAuth). In rfb/dh.cpp the Diffie-Hellman key exchange is performed with parameters that fit in an unsigned 64-bit integer (DHMAX_BITS controls the prime size). A 64-bit DH key can be…
When was CVE-2026-7830 disclosed?
CVE-2026-7830 was first published 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-2026-7830 actively exploited?
CVE-2026-7830 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (19th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-7830?
CVE-2026-7830 has a CVSS base score of 7.4 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-7830?
No fix for CVE-2026-7830 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-7830 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-7830

Explore →

Is Your Infrastructure Affected by CVE-2026-7830?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs