Google: sys-kernel/cchost-kernel-6_12, sys-kernel/csql-kernel-6_12, sys-kernel/lakitu-kernel-6_12, sys-kernel/lakitu-nc-kernel-6_12: security update to 19506.299.60

high Tenable Self-Hosted Container Security Plugin ID 470416

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: apparmor: fix use-after-free in
rawdata dedup loop aa_replace_profiles() walks ns->rawdata_list to dedup the incoming policy blob against
entries already attached to existing profiles. Per the kernel-doc on struct aa_loaddata, list membership
does not hold a reference: profiles hold pcount, and when the last pcount drops, do_ploaddata_rmfs() is
queued on a workqueue that takes ns->lock and removes the entry. Between dropping the last pcount and the
workqueue running, an entry remains on the list with pcount == 0. aa_get_profile_loaddata() is an
unconditional kref_get() on pcount, so when the dedup loop hits such an entry, refcount hardening reports
refcount_t: addition on 0; use-after-free. inside aa_replace_profiles(), and the poisoned counter then
trips "saturated" and "underflow" warnings on the subsequent uses of the same loaddata. Before commit
a0b7091c4de4 ("apparmor: fix race on rawdata dereference") the dedup path used a get_unless_zero-style
helper on a single counter, so the existing "if (tmp)" guard was meaningful. The split-refcount refactor
introduced aa_get_profile_loaddata(), which has plain kref_get() semantics, and the guard quietly became a
no-op. Introduce aa_get_profile_loaddata_not0(), matching the existing _not0 convention used by
aa_get_profile_not0(), and use it for the rawdata_list dedup lookup so dying entries are skipped.
Reproduced on x86_64 with v7.1-rc5 in QEMU+KVM running Ubuntu 24.04 + stress-ng 0.17.06: stress-ng
--apparmor 1 --klog-check --timeout 60s Without this patch the three refcount_t warnings fire within a few
seconds. With it the same 60 s run is clean. Coverage is a smoke-test only; a longer soak with
CONFIG_KASAN, CONFIG_KCSAN and CONFIG_PROVE_LOCKING would be welcome from anyone with the cycles.
(CVE-2026-63827)

Solution

Update the sys-kernel/cchost-kernel-6_12 library and its related packages to version 19506.299.60 or later.

Plugin Details

Severity: High

ID: 470416

Version: Revision 1.5

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: Medium

Score: 4.9

Percentile: 58.27

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-2026-63827

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-2026-63827

Detections

Analytics