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 471374

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: mm/page_alloc: fix initialization of
tags of the huge zero folio with init_on_free __GFP_ZEROTAGS semantics are currently a bit weird, but
effectively this flag is only ever set alongside __GFP_ZERO and __GFP_SKIP_KASAN. If we run with
init_on_free, we will zero out pages during __free_pages_prepare(), to skip zeroing on the allocation
path. However, when allocating with __GFP_ZEROTAG set, post_alloc_hook() will consequently not only skip
clearing page content, but also skip clearing tag memory. Not clearing tags through __GFP_ZEROTAGS is
irrelevant for most pages that will get mapped to user space through set_pte_at() later: set_pte_at() and
friends will detect that the tags have not been initialized yet (PG_mte_tagged not set), and initialize
them. However, for the huge zero folio, which will be mapped through a PMD marked as special, this
initialization will not be performed, ending up exposing whatever tags were still set for the pages. The
docs (Documentation/arch/arm64/memory-tagging-extension.rst) state that allocation tags are set to 0 when
a page is first mapped to user space. That no longer holds with the huge zero folio when init_on_free is
enabled. Fix it by decoupling __GFP_ZEROTAGS from __GFP_ZERO, passing to tag_clear_highpages() whether we
want to also clear page content. Invert the meaning of the tag_clear_highpages() return value to have
clearer semantics. Reproduced with the huge zero folio by modifying the check_buffer_fill arm64/mte
selftest to use a 2 MiB area, after making sure that pages have a non-0 tag set when freeing (note that,
during boot, we will not actually initialize tags, but only set KASAN_TAG_KERNEL in the page flags). $
./check_buffer_fill 1..20 ... not ok 17 Check initial tags with private mapping, sync error mode and mmap
memory not ok 18 Check initial tags with private mapping, sync error mode and mmap/mprotect memory ...
This code needs more cleanups; we'll tackle that next, like decoupling __GFP_ZEROTAGS from
__GFP_SKIP_KASAN. [[email protected]: s/__GPF_ZERO/__GFP_ZERO/, per David] (CVE-2026-64130)

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: 471374

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: 23.72

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-2026-64130

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-2026-64130

Detections

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