CVE-2026-40317: NovumOS is a custom 32-bit operating system written in Zig and x86 Assembly

Q: How do I fix CVE-2026-40317?

novumos: upgrade to 0.24. Exact commands for each OS are on this page.

Q: Is CVE-2026-40317 being exploited?

CVE-2026-40317 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-40317 affect?

CVE-2026-40317 affects novumos. Severity is critical (CVSS 9.3). 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-

Q: How urgent is CVE-2026-40317?

Priority 41/100. Critical severity; Public exploit reference

This month

CRITICAL 9.3UPGRADE

CVE-2026-40317 is a critical-severity flaw (CVSS 9.3) affecting novumos. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Critical severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	9.3 (Critical)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 87%)
CISA exploited list	No
Weakness	CWE-20, CWE-269
Published	2026-04-18
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: minecanton209

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-18 01:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

minecanton209 novumos UPGRADE

Affected: < 0.24

Fixed in: 0.24

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-40317?

novumos: upgrade to 0.24. Exact commands for each OS are on this page.

Is CVE-2026-40317 being exploited?

CVE-2026-40317 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-40317 affect?

CVE-2026-40317 affects novumos. Severity is critical (CVSS 9.3). 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-

How urgent is CVE-2026-40317?

Priority 41/100. Critical severity; Public exploit reference

Related CVEs

CVE-2026-40572 CRITICAL 9.0 UPGRADE NovumOS is a custom 32-bit operating system written in Zig and x86 Assembly

References

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