Is CVE-2026-40317 in the CISA KEV catalog?

No. CVE-2026-40317 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-40317?

CVE-2026-40317 has a CVSS v3 base score of 9.3 (CRITICAL).

What is the EPSS score for CVE-2026-40317?

CVE-2026-40317 has an EPSS score of 0.22% (13th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-40317?

Upgrade novumos to 0.24 or later.

CVE & CISA-KEV Catalog

CVE-2026-40317

CRITICAL

9.3

CVSS v3

NVD

Description

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.

CWE-20Improper Input Validation CWE-269Improper Privilege Management

How to fix

Remediation Available

novumosNVD

Affected:< 0.24Fixed in:0.24CVE-2026-40317derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploit Intelligence

0.22%probability of exploitation in 30 days

13thpercentile

Low risk: more likely to be exploited than 13% of all known CVEs.

References

Exploit1

github.com

Release Notes1

github.com

Related Vulnerabilities

Other CWE-20 (Improper Input Validation) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-3400	Critical	10.0	100%	KEV + Ransom	-
CVE-2021-45105	Medium	5.9	100%	-	Fix
CVE-2021-44228	Critical	10.0	100%	KEV + Ransom	Fix
CVE-2021-21985	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2018-7600	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2020-3452	High	7.5	100%	KEV	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-27.