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Fencer Vulns
high 7.9

CVE-2026-46076 json

KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1

published 2026-05-27 5 mo ago modified 2026-10-21 18 d ago also EUVD-2026-32458

cvss
7.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

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]

Patch / fix

  • Linux Linux 6.6.160, 6.12.86, 6.18.27, 7.0.4, 7.1
  • linux Debian 13 6.12.86-1
  • linux Debian 14 7.0.4-1

debian advisories DEBIAN-CVE-2026-46076

  • linux Ubuntu 24.04 LTS 6.8.0-136.136
  • linux Ubuntu 26.04 LTS 7.0.0-27.27
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1061.64
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1008.8
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1064.72
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1007.7
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1059.67
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1061.62

ubuntu advisories UBUNTU-CVE-2026-46076

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9 5.14.0-687.55.1.el9_8
  • rv RHEL 9 5.14.0-687.55.1.el9_8
  • perf RHEL 9 5.14.0-687.55.1.el9_8
  • rtla RHEL 9 5.14.0-687.55.1.el9_8
  • libperf RHEL 9 5.14.0-687.55.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.55.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.55.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.55.1.el9_8

red hat advisories RHSA-2026:76739RHSA-2026:72624

  • kernel-default SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Live Patching 15 SP6 +1 more 6.4.0-150600.23.125.1
  • kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.36.1
  • kernel-obs-build Linux Micro Extras 6.2 6.12.0-160000.36.1
  • kernel-rt Linux Micro 6.2 6.12.0-160000.36.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.36.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.36.1
  • kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.36.1
  • kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.36.1.160000.2.17

suse advisories SUSE-SU-2026:3156-1SUSE-SU-2026:22742-1SUSE-SU-2026:22769-1SUSE-SU-2026:22835-1SUSE-SU-2026:22812-1SUSE-SU-2026:2800-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.36.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.36.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.36.1

opensuse advisories openSUSE-SU-2026:21388-1openSUSE-SU-2026:10954-1

  • kernel AlmaLinux 10 6.12.0-211.61.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.61.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.61.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.61.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.61.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.61.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.61.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.61.1.el10_2

almalinux advisories ALSA-2026:72624

  • kernel Rocky Linux 10 6.12.0-211.61.1.el10_2

rocky linux advisories RLSA-2026:72624

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-46076 updated cvss 7.0

kernel: KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1

  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.55.1.el9_8, perf 5.14.0-687.55.1.el9_8, rtla 5.14.0-687.55.1.el9_8, python3-perf 5.14.0-687.55.1.el9_8, kernel-devel-matched 5.14.0-687.55.1.el9_8, kernel-64k-devel-matched 5.14.0-687.55.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:76739
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.61.1.el10_2, perf 6.12.0-211.61.1.el10_2, rtla 6.12.0-211.61.1.el10_2, python3-perf 6.12.0-211.61.1.el10_2, kernel-devel-matched 6.12.0-211.61.1.el10_2, kernel-64k-devel-matched 6.12.0-211.61.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:72624
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.55.1.el9_8, kernel-64k 5.14.0-687.55.1.el9_8, kernel-core 5.14.0-687.55.1.el9_8, kernel-tools 5.14.0-687.55.1.el9_8, kernel-modules 5.14.0-687.55.1.el9_8, kernel-64k-core 5.14.0-687.55.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:76739
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.61.1.el10_2, kernel-64k 6.12.0-211.61.1.el10_2, kernel-core 6.12.0-211.61.1.el10_2, kernel-tools 6.12.0-211.61.1.el10_2, kernel-modules 6.12.0-211.61.1.el10_2, kernel-64k-core 6.12.0-211.61.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:72624
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.55.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.55.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.55.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.55.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.55.1.el9_8
    fixed: vendor fix RHSA-2026:76739
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.61.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.61.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.61.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.61.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.61.1.el10_2
    fixed: vendor fix RHSA-2026:72624
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.55.1.el9_8, kernel-rt-64k 5.14.0-687.55.1.el9_8, kernel-rt-core 5.14.0-687.55.1.el9_8, kernel-rt-modules 5.14.0-687.55.1.el9_8, kernel-rt-64k-core 5.14.0-687.55.1.el9_8, kernel-rt-debug-core 5.14.0-687.55.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:76739
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.61.1.el10_2, kernel-rt-64k 6.12.0-211.61.1.el10_2, kernel-rt-core 6.12.0-211.61.1.el10_2, kernel-rt-modules 6.12.0-211.61.1.el10_2, kernel-rt-64k-core 6.12.0-211.61.1.el10_2, kernel-rt-debug-core 6.12.0-211.61.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:72624
show 3 more
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.55.1.el9_8, kernel-rt-core 5.14.0-687.55.1.el9_8, kernel-rt-modules 5.14.0-687.55.1.el9_8, kernel-rt-debug-core 5.14.0-687.55.1.el9_8, kernel-rt-modules-core 5.14.0-687.55.1.el9_8, kernel-rt-debug-modules 5.14.0-687.55.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:76739
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.61.1.el10_2, kernel-rt-core 6.12.0-211.61.1.el10_2, kernel-rt-modules 6.12.0-211.61.1.el10_2, kernel-rt-debug-core 6.12.0-211.61.1.el10_2, kernel-rt-modules-core 6.12.0-211.61.1.el10_2, kernel-rt-debug-modules 6.12.0-211.61.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:72624
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
23 d ago

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.9 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.