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 20085.0.0

medium Tenable Cloud Security Plugin ID 470706

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: binfmt_misc: don't warn when the mount
is completed from another user namespace fsopen() records the caller's user namespace in fc->user_ns and
hands back an ordinary file descriptor. Nothing ties the task that calls fsconfig(FSCONFIG_CMD_CREATE) to
the task that created the context. The fd is inherited across fork() and exec() and it can be passed over
a unix socket. Completing a context from another user namespace is allowed on purpose. vfs_cmd_create()
authorizes the create with mount_capable(), which for FS_USERNS_MOUNT checks ns_capable(fc->user_ns,
CAP_SYS_ADMIN), and that succeeds for a task holding CAP_SYS_ADMIN in an ancestor of fc->user_ns. So an
unprivileged task can reach the WARN_ON() in bm_fill_super(): create a user and a mount namespace in a
child, call fsopen("binfmt_misc") there, send the fscontext fd to the parent and let the parent issue
FSCONFIG_CMD_CREATE. Both namespaces come from a plain unshare(1) and no capability is needed anywhere:
WARNING: fs/binfmt_misc.c:938 at bm_fill_super+0xa2/0xc0 [binfmt_misc] CPU: 15 UID: 1000 PID: 3243382
Comm: fswarn Call Trace: get_tree_keyed+0x7d/0xb0 bm_get_tree+0x34/0x90 [binfmt_misc]
vfs_get_tree+0x2a/0x100 vfs_cmd_create+0x60/0xf0 __do_sys_fsconfig+0x4b2/0x500 The child needs the mount
namespace because fsopen() itself gates on may_mount(), which asks for CAP_SYS_ADMIN in the user namespace
owning the caller's mount namespace. fsconfig() doesn't repeat that check. It is a WARN_ON() and not a
WARN_ON_ONCE(), so the condition can be raised in a loop to taint the kernel and flood the log, and it
panics a kernel booted with panic_on_warn. Keep refusing the mount and stop warning about it. Nothing in
bm_fill_super() depends on the two namespaces matching, it derives everything from sb->s_user_ns.
(CVE-2026-74618)

Solution

Update the sys-kernel/cchost-kernel-6_18 library and its related packages to version 20085.0.0 or later.

Plugin Details

Severity: Medium

ID: 470706

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: Low

Score: 3

Percentile: 23.62

Vendor

Vendor Severity: LOW

CVSS v2

Risk Factor: High

Base Score: 7.2

Temporal Score: 5.3

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

CVSS Score Source: CVE-2026-74618

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: 8/22/2026

Reference Information

CVE: CVE-2026-74618

Detections

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