Google: sys-kernel/cchost-kernel-6_18, sys-kernel/csql-kernel-6_18, sys-kernel/lakitu-kernel-6_18, sys-kernel/lakitu-nc-kernel-6_18: security update to 19862.0.0

medium Tenable Self-Hosted Container Security Plugin ID 470811

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: iommu/amd: Bounds-check devid in
__rlookup_amd_iommu() iommu_device_register() walks every device on the PCI bus via bus_for_each_dev() and
calls amd_iommu_probe_device() for each. The inlined check_device() path computes the device's sbdf, calls
rlookup_amd_iommu() to find the owning IOMMU, and only afterwards verifies devid <= pci_seg->last_bdf.
__rlookup_amd_iommu() indexes rlookup_table[devid] with no bounds check of its own, so for a PCI device
whose BDF is not described by the IVRS, the lookup reads past the end of the allocation before the
caller's bounds check can run. This was harmless before commit e874c666b15b ("iommu/amd: Change rlookup,
irq_lookup, and alias to use kvalloc()"): the table was a zeroed page-order allocation, so the over-read
returned NULL and the caller's NULL check skipped the device. After that commit the table is a tight
kvcalloc() and the over-read returns adjacent slab contents, which check_device() then dereferences as a
struct amd_iommu *, causing a boot-time GPF. Seen on Google Compute Engine ct6e VMs, where the virtualized
IVRS describes only the four TPU endpoints 00:04.0-07.0; the gVNIC at 00:08.0 (devid 0x40) indexes 56
bytes past the 456-byte allocation, into the adjacent kmalloc-512 slab object: pci 0000:00:04.0: Adding to
iommu group 0 pci 0000:00:05.0: Adding to iommu group 1 pci 0000:00:06.0: Adding to iommu group 2 pci
0000:00:07.0: Adding to iommu group 3 Oops: general protection fault, probably for non-canonical address
0x3a64695f78746382: 0000 [#1] SMP NOPTI CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.18.22 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/06/2025 RIP:
0010:amd_iommu_probe_device+0x54/0x3a0 Call Trace: __iommu_probe_device+0x107/0x520
probe_iommu_group+0x29/0x50 bus_for_each_dev+0x7e/0xe0 iommu_device_register+0xc9/0x240
iommu_go_to_state+0x9c0/0x1c60 amd_iommu_init+0x14/0x40 pci_iommu_init+0x16/0x60
do_one_initcall+0x47/0x2f0 Guard the array access in __rlookup_amd_iommu(). With the fix applied on
6.18.22, the gVNIC at 00:08.0 is skipped cleanly and the VM boots. (CVE-2026-53283)

Solution

Update the sys-kernel/cchost-kernel-6_18 library and its related packages to version 19862.0.0 or later.

Plugin Details

Severity: Medium

ID: 470811

Version: Revision 1.6

Type: Local

Family: Google COS Security Checks

Published: 10/3/2026

Updated: 10/6/2026

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

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.75

Vendor

Vendor Severity: MEDIUM

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.4

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

CVSS Score Source: CVE-2026-53283

CVSS v3

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 4.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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: 6/22/2026

Reference Information

CVE: CVE-2026-53283

Detections

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