CVE-2026-46076
In the Linux kernel, the following vulnerability has been resolved: KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1 Explicitly synthesize a #UD for VMMCALL if L2 is active, L1 does NOT want to intercept VMMCALL,…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.12%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
In the Linux kernel, the following vulnerability has been resolved: KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1 Explicitly synthesize a #UD for VMMCALL if L2 is active, L1 does NOT want to intercept VMMCALL, nested_svm_l2_tlb_flush_enabled() is true, and the hypercall is something other than one of the supported Hyper-V hypercalls. When all of the above conditions are met, KVM will intercept VMMCALL but never forward it to L1, i.e. will let L2 make hypercalls as if it were L1. The TLFS says a whole lot of nothing about this scenario, so go with the architectural behavior, which says that VMMCALL #UDs if it's not intercepted. Opportunistically do a 2-for-1 stub trade by stub-ifying the new API instead of the helpers it uses. The last remaining "single" stub will soon be dropped as well. [sean: rewrite changelog and comment, tag for stable, remove defunct stubs]
- CVSS 3.1
- 7.9 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H
- EPSS
- 0.12% probability · 2th percentile
- CISA KEV
- Not listed
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/009c0f726abeaa67aad1d96b883bdce01d405ce2Patch
- https://git.kernel.org/stable/c/5fb4a5f361565f5b629d8a8fe5288ce8463c5727Patch
- https://git.kernel.org/stable/c/924d721fae95687acedbaf624a094ed0e8b67104Patch
- https://git.kernel.org/stable/c/c36991c6f8d2ab56ee67aff04e3c357f45cfc76cPatch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.