Is there a public exploit for CVE-2026-99186?

No public exploit for CVE-2026-99186 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: x86/insn-eval: Fix shadowed segment index in getsegregoverrideidx()…

CVE-2026-99186

In the Linux kernel, the following vulnerability has been resolved: x86/insn-eval: Fix shadowed segment index in getsegregoverrideidx() Commit 45e1dccc0653 ("x86/insn: Simplify foreachinsnprefix()") made foreachinsnprefix() declare its own loop counter named idx. getsegregoverrideidx() keeps its result in a local of the same name, so the assignments in the loop body now write the loop counter: the function always returns INATSEGREGDEFAULT, so FS and GS overrides are ignored; a CS override sets the counter to INATSEGREGCS (2), the increment makes it 3, and prefixes.bytes[3] holds the last prefix, 0x2e again, so the loop never terminates. The UMIP emulation reaches this from the #GP handler for user space: an SGDT, SIDT or SMSW with a memory operand and a CS prefix leaves the task spinning in the kernel, never returning to user space, with a SIGKILL that is never delivered. Any user can thus tie up CPUs until reboot. With an FS or GS prefix, the emulated result is written to the wrong address. Rename the internal macro iterator variable. [ Lukas' original patch renamed the use site, I changed it to rename the iterator in the macro instead, but left Lukas' commit message and…

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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