VulnerabilityPublished 28 Oct 2026

CVE-2026-99168: Linux kernel · mshv_vtl: Check per-CPU register page before mmap

Affects Linux kernelSource CVE Database V5

Not known to be exploited : upgrade to 874194a8de75fc2f4d1fb70c670b289b7e48f93e or 5c0757b065fbd140d8fbd05dc2c2146b713dfa68 when convenient.

Data as of 28 Oct 2026, 10:58 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

Patch: Available – fixed in 874194a8de75fc2f4d1fb70c670b289b7e48f93e, 5c0757b065fbd140d8fbd05dc2c2146b713dfa68

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to 874194a8de75fc2f4d1fb70c670b289b7e48f93e or 5c0757b065fbd140d8fbd05dc2c2146b713dfa68.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 7bfe3b8ea6e30437e01fcb8e4f56ef6e4d986d0f, < 874194a8de75fc2f4d1fb70c670b289b7e48f93e	Fixed in 874194a8de75fc2f4d1fb70c670b289b7e48f93e
LinuxLinux	Affected ≥ 7bfe3b8ea6e30437e01fcb8e4f56ef6e4d986d0f, < 5c0757b065fbd140d8fbd05dc2c2146b713dfa68	Fixed in 5c0757b065fbd140d8fbd05dc2c2146b713dfa68
LinuxLinux	Affected =6.19	Fixed in–
Debiandebian/linux`pkg:deb/debian/linux`Other threats	Affected =6.19	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

In the Linux kernel, the following vulnerability has been resolved: mshv_vtl: Check per-CPU register page before mmap Register-page setup is optional for each CPU. If allocation or registration fails, mshv_vtl_configure_reg_page() warns and leaves that CPU's reg_page NULL, but initial context setup continues successfully. Meanwhile, successful setup on another CPU sets the global mshv_has_reg_page flag. mshv_vtl_fault() checks this global flag before selecting the requested CPU's register page. With mixed setup results across online CPUs, the check passes even for a CPU with no register page, reaching get_page(NULL) when userspace faults in that mapping. Check the selected per-CPU register page before taking its reference and return VM_FAULT_SIGBUS if it is absent.

References

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