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 19999.44.21

medium Tenable Cloud Security Plugin ID 470625

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: perf/x86/amd/core: Avoid enabling BRS
from the SVM reload path Branch Sampling (BRS) and Last Branch Record (LBR) are mutually exclusive
hardware features, and users of both are tracked via cpuc->lbr_users. When SVM is toggled on a CPU, the
host perf events are reprogrammed to update the HostOnly filter bit (set when virtualization is enabled,
cleared when it is disabled). On PerfMonV2-capable processors, this reprogramming is performed by calling
amd_pmu_enable_all() to rewrite the event selectors. However, amd_pmu_enable_all() also calls
amd_brs_enable_all(), which enables BRS whenever cpuc->lbr_users > 0. Having active LBR events satisfies
this gating on processors that have LBR but not BRS. The kernel then tries to set the BRS enable bit in
DebugExtnCfg (MSR 0xc000010f). Since that bit is deprecated on such hardware, the write results in a #GP:
Call Trace: <IRQ> amd_pmu_enable_all+0x1d/0x90 amd_pmu_disable_virt+0x62/0xb0
kvm_arch_disable_virtualization_cpu+0xa/0x40 [kvm] hardware_disable_nolock+0x1a/0x30 [kvm]
__flush_smp_call_function_queue+0x9b/0x410 __sysvec_call_function+0x18/0xc0 sysvec_call_function+0x69/0x90
</IRQ> <TASK> asm_sysvec_call_function+0x16/0x20 RIP: 0010:cpuidle_enter_state+0xc4/0x450 ?
cpuidle_enter_state+0xb7/0x450 cpuidle_enter+0x29/0x40 cpuidle_idle_call+0xf5/0x160 do_idle+0x7b/0xe0
cpu_startup_entry+0x26/0x30 start_secondary+0x115/0x140 secondary_startup_64_no_verify+0x194/0x19b </TASK>
Fix this by ensuring that BRS is not enabled from the event selector reprogramming path even when
cpuc->lbr_users > 0. (CVE-2026-72325)

Solution

Update the sys-kernel/cchost-kernel-6_12 library and its related packages to version 19999.44.21 or later.

Plugin Details

Severity: Medium

ID: 470625

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: 23.59

Vendor

Vendor Severity: LOW

CVSS v2

Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.2

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

CVSS Score Source: CVE-2026-72325

CVSS v3

Risk Factor: Medium

Base Score: 4.4

Temporal Score: 3.9

Vector: CVSS:3.0/AV:L/AC:L/PR:H/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: 8/11/2026

Reference Information

CVE: CVE-2026-72325

Detections

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