CVE-2026-40317

CRITICALNVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.3 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 87% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
9.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.3Exploit: Elevated riskExposed: 0

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

NovumOS is a custom 32-bit operating system written in Zig and x86 Assembly. In versions prior to 0.24, Syscall 12 (JumpToUser) accepts an arbitrary entry point address from user-space registers without validation, allowing any Ring 3 user-mode process to jump to kernel addresses and execute arbitrary code in Ring 0 context, resulting in local privilege escalation. This issue has been fixed in version 0.24. If developers are unable to immediately update, they should restrict syscall access by running the system in single-user mode without Ring 3, and disable user-mode processes by only running kernel shell with no user processes. This issue has been fixed in version 0.24.

CVSS v3
9.3
EG Score
9.3(medium)
EG Risk
58(Track*)
EG Risk 58/100SSVC: 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
Severity93% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
13%
KEV
Not listed

Published

April 18, 2026

Last Modified

April 27, 2026

Advisory Details (2)

Auto-updated May 1, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Arbitrary Code Execution via Syscall 12 (JumpToUser) · Advisory · MinecAnton209/NovumOS · GitHub

Affected: v0.24

https://github.com/MinecAnton209/NovumOS/security/advisories/GHSA-xjx3-gjh9-45fm
generic

Release v0.24: Ironclad (Security & Watchdog) · MinecAnton209/NovumOS · GitHub

https://github.com/MinecAnton209/NovumOS/releases/tag/v0.24

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 38× 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.

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

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Frequently asked(5)

What is CVE-2026-40317?
CVE-2026-40317 is a critical vulnerability published on April 18, 2026. NovumOS is a custom 32-bit operating system written in Zig and x86 Assembly. In versions prior to 0.24, Syscall 12 (JumpToUser) accepts an arbitrary entry point address from user-space registers without validation, allowing any Ring 3 user-mode process to jump to kernel addresses and execute…
When was CVE-2026-40317 disclosed?
CVE-2026-40317 was first published in the National Vulnerability Database on April 18, 2026, with the most recent update on April 27, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40317 actively exploited?
CVE-2026-40317 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 86.6% of all scored CVEs.
What is the CVSS score of CVE-2026-40317?
CVE-2026-40317 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2026-40317?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40317, 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.

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