Google: sys-kernel/cchost-kernel-6_12, sys-kernel/cchost-kernel-6_18, sys-kernel/csql-kernel-6_12, sys-kernel/csql-kernel-6_18, sys-kernel/lakitu-kernel-6_12, sys-kernel/lakitu-kernel-6_18, sys-kernel/lakitu-nc-kernel-6_12, sys-kernel/lakitu-nc-kernel-6_18: security update to 19804.0.0

high Tenable Self-Hosted Container Security Plugin ID 470024

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

- In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Fix shadow paging use-after-
free due to unexpected GFN The shadow MMU computes GFNs for direct shadow pages using sp->gfn plus the
SPTE index. This assumption breaks for shadow paging if the guest page tables are modified between VM
entries (similar to commit aad885e77496, "KVM: x86/mmu: Drop/zap existing present SPTE even when creating
an MMIO SPTE", 2026-03-27). The flow is as follows: - a PDE is installed for a 2MB mapping, and a page in
that area is accessed. KVM creates a kvm_mmu_page consisting of 512 4KB pages; the kvm_mmu_page is marked
by FNAME(fetch) as direct-mapped because the guest's mapping is a huge page (and thus contiguous). - the
PDE mapping is changed from outside the guest. - the guest accesses another page in the same 2MB area. KVM
installs a new leaf SPTE and rmap entry; the SPTE uses the "correct" GFN (i.e. based on the new mapping,
as changed in the previous step) but that GFN is outside of the [sp->gfn, sp->gfn + 511] range; therefore
the rmap entry cannot be found and removed when the kvm_mmu_page is zapped. - the memslot that covers the
first 2MB mapping is deleted, and the kvm_mmu_page for the now-invalid GPA is zapped. However,
rmap_remove() only looks at the [sp->gfn, sp->gfn + 511] range established in step 1, and fails to find
the rmap entry that was recorded by step 3. - any operation that causes an rmap walk for the same page
accessed by step 3 then walks a stale rmap and dereferences a freed kvm_mmu_page. This includes dirty
logging or MMU notifier invalidations (e.g., from MADV_DONTNEED). The underlying issue is that KVM's
walking of shadow PTEs assumes that if a SPTE is present when KVM wants to install a non-leaf SPTE, then
the existing kvm_mmu_page must be for the correct gfn. Because the only way for the gfn to be wrong is if
KVM messed up and failed to zap a SPTE... which shouldn't happen, but *actually* only happens in response
to a guest write. That bug dates back literally forever, as even the first version of KVM assumes that the
GFN matches and walks into the "wrong" shadow page. However, that was only an imprecision until
2032a93d66fa ("KVM: MMU: Don't allocate gfns page for direct mmu pages") came along. Fix it by checking
for a target gfn mismatch and zapping the existing SPTE. That way the old SP and rmap entries are gone,
KVM installs the rmap in the right location, and everyone is happy. (CVE-2026-46113)

Solution

Update the sys-kernel/cchost-kernel-6_12 library and its related packages to version 19804.0.0 or later.

Plugin Details

Severity: High

ID: 470024

Version: Revision 1.3

Type: Local

Family: Google COS Security Checks

Published: 10/3/2026

Updated: 10/3/2026

Supported Sensors: Tenable Cloud Security, Tenable Self-Hosted Container Security

Risk Information

VPR

Risk Factor: High

Score: 7

Percentile: 98.23

Vendor

Vendor Severity: LOW

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

Vector: CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C

CVSS Score Source: CVE-2026-46113

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 7.7

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 5/26/2026

Reference Information

CVE: CVE-2026-46113

Detections

Analytics