Is there a public exploit for CVE-2026-99120?

No public exploit for CVE-2026-99120 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

— Unscored

In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Cope with the SS bit being set in #NPF exit codes When…

CVE-2026-99120

In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Cope with the SS bit being set in #NPF exit codes When running Hyper-V from Windows 11, KVM is seeing the SS bit set in nested page fault error codes produced for shadowed NPT. The AMD manual is unclear about when SS is set, including whether it can be set when SupervisorShadowStackEn (bit 6) is not set in the MISCCTL field of the VMCB. Nevertheless, the unexpected SS bit causes out of bounds accesses in permissionfault(), seen as either WARNs or UBSAN reports: kernel: UBSAN: array-index-out-of-bounds in arch/x86/kvm/mmu.h:225:27 kernel: index 34 is out of range for type 'u16 [16]' (in this case, the page fault error code is 342=0x44, i.e. SS|U; the report shows SS|U|W happening as well). Fix the handling of unknown error codes by dropping SS and (with a WARN) any bits not among those that permissionfault() expects to receive. At the same time, given the uncertainty about when hardware sets SS, follow the processor's behavior when constructing the fault's error code, and preserve the SS bit as passed to FNAME(walkaddrgeneric). While the behavior is surprising, there's a possibility that Hyper-V…

Assessment

CVSS: Not yet scored
Severity: Unscored
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 28 October 2026
Last updated: 28 October 2026
Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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