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 20198.0.0

high Tenable Cloud Security Plugin ID 475753

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: btrfs: zoned: don't clobber the extent
buffer when zeroing it out On a zoned filesystem a freed-but-still-dirty tree block is written out as
zeros (EXTENT_BUFFER_ZONED_ZEROOUT) only to keep the zone write pointer advancing. btree_csum_one_bio()
implemented this by memzeroing the extent buffer's own folios before submission. That destroys the in-
memory buffer while it may still be referenced. In particular btrfs_free_tree_block() can run on it
afterwards and reads the header to add a delayed reference; once the header has been zeroed it frees
bytenr 0 and corrupts the extent tree (the btrfs_header_bytenr(buf) != 0 ASSERT in
btrfs_free_tree_block(), or an "unable to find ref" abort). It is flaky and reproduces under fsstress,
e.g. generic/461 and generic/013. Write the zeros to disk from the shared zero page instead and leave the
extent buffer content untouched, so any later reference - including the delayed reference from
btrfs_free_tree_block() - still sees a valid header. end_bbio_meta_write() now clears writeback on the
buffer's own folios, as the bio no longer carries them. (CVE-2026-90260)

Solution

Update the sys-kernel/cchost-kernel-6_18 library and its related packages to version 20198.0.0 or later.

Plugin Details

Severity: High

ID: 475753

Version: Revision 1.1

Type: Local

Family: Google COS Security Checks

Published: 10/16/2026

Updated: 10/16/2026

Risk Information

VPR

Risk Factor: Medium

Score: 4.3

Percentile: 53.41

Vendor

Vendor Severity: LOW

CVSS v2

Risk Factor: Medium

Base Score: 6.2

Temporal Score: 4.6

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

CVSS Score Source: CVE-2026-90260

CVSS v3

Risk Factor: High

Base Score: 7.1

Temporal Score: 6.2

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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: 9/17/2026

Reference Information

CVE: CVE-2026-90260

Detections

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