Google: sys-kernel/cchost-kernel-6_12, sys-kernel/csql-kernel-6_12, sys-kernel/csql-kernel-6_6, sys-kernel/lakitu-kernel-6_12, sys-kernel/lakitu-kernel-6_6, sys-kernel/lakitu-nc-kernel-6_12, sys-kernel/lakitu-nc-kernel-6_6, sys-kernel/lakitu-vgpu-kernel-6_6: security update to 19216.532.42

high Tenable Self-Hosted Container Security Plugin ID 469216

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: bpf: use kvfree() for replaced sysctl
write buffer proc_sys_call_handler() allocates its temporary sysctl buffer with kvzalloc() and passes it
to __cgroup_bpf_run_filter_sysctl(). Since kvzalloc() may fall back to vmalloc() for large allocations,
freeing that buffer with kfree() is wrong and can corrupt memory. Use kvfree() to safely handle both
kmalloc and kvzalloc()/vmalloc allocations. The bug was first flagged by an experimental analysis tool we
are developing for kernel memory-management bugs while analyzing v6.13-rc1. The tool is still under
development and is not yet publicly available. Manual inspection confirms that the bug is still present in
v7.1-rc5. Reproduced the bug based on v7.1-rc4 in a QEMU x86_64 guest booted with KASAN and
CONFIG_FAILSLAB enabled. To exercise the replacement path, the test tree also included the accompanying
fix for the stale ret == 1 check in __cgroup_bpf_run_filter_sysctl(). The reproducer confines failslab
injections to the proc_sys_call_handler() range, uses stacktrace-depth=32, and injects fail-nth=1 while
writing 8191 bytes to /proc/sys/kernel/domainname from a task in the target cgroup. Under that setup,
fail-nth=1 triggered the fault: BUG: unable to handle page fault for address: ffffeb0200024d48 #PF:
supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops:
0000 SMP KASAN NOPTI CPU: 2 UID: 0 PID: 209 Comm: repro_proc_sys_ Not tainted
7.1.0-rc4-00686-g97625979a5d4 PREEMPT(lazy) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
1.15.0-1 04/01/2014 RIP: 0010:kfree+0x6e/0x510 ... Call Trace: <TASK> ?
__cgroup_bpf_run_filter_sysctl+0x626/0xc30 __cgroup_bpf_run_filter_sysctl+0x74d/0xc30 ?
__pfx___cgroup_bpf_run_filter_sysctl+0x10/0x10 ? srso_return_thunk+0x5/0x5f ?
__kvmalloc_node_noprof+0x345/0x870 ? proc_sys_call_handler+0x250/0x480 ? srso_return_thunk+0x5/0x5f
proc_sys_call_handler+0x3a2/0x480 ? __pfx_proc_sys_call_handler+0x10/0x10 ? srso_return_thunk+0x5/0x5f ?
selinux_file_permission+0x39f/0x500 ? srso_return_thunk+0x5/0x5f ? lock_is_held_type+0x9e/0x120
vfs_write+0x98e/0x1000 ... </TASK> With this fix applied on top of the same test setup, rerunning the
reproducer with fail-nth=1 yields no corresponding Oops reports. (CVE-2026-63809)

Solution

Update the sys-kernel/cchost-kernel-6_12 library and its related packages to version 19216.532.42 or later.

Plugin Details

Severity: High

ID: 469216

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: 7.6

Percentile: 98.37

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-2026-63809

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/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: 7/8/2026

Reference Information

CVE: CVE-2026-63809

Detections

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