Google: sys-kernel/cchost-kernel-6_12, sys-kernel/cchost-kernel-6_18, sys-kernel/csql-kernel-6_12, sys-kernel/csql-kernel-6_18, sys-kernel/lakitu-kernel-6_12, sys-kernel/lakitu-kernel-6_18, sys-kernel/lakitu-nc-kernel-6_12, sys-kernel/lakitu-nc-kernel-6_18: security update to 19999.44.28

medium Tenable Self-Hosted Container Security Plugin ID 471259

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 leak the user
namespace when the mount fails bm_get_tree() takes a reference to the user namespace and hands it to
get_tree_keyed() as the sget key. sget_fc() moves that reference into sb->s_fs_info and clears
fc->s_fs_info, so from that point on the superblock owns it and bm_free() doesn't see it anymore. The
superblock drops it in ->put_super(). But generic_shutdown_super() only calls ->put_super() from inside
the if (sb->s_root) branch, so nothing releases it when bm_fill_super() fails: - The kzalloc_obj() failure
leaves s_root NULL and the whole branch is skipped. - A simple_fill_super() failure in the file loop
leaves s_root set, but s_op still points at simple_super_operations, which has no ->put_super().
bm_fill_super() installs s_ops only once simple_fill_super() returned success, and installing it earlier
wouldn't help either because simple_fill_super() overwrites s_op. Either way vfs_get_super() calls
deactivate_locked_super() and the reference is gone for good. binfmt_misc mounts are available in a user
namespace and both the inode and the dentry cache are SLAB_ACCOUNT, so an unprivileged caller under a
tight memory cgroup can fail simple_fill_super() on demand and leak one user namespace per attempt. Drop
the reference in ->kill_sb() instead, which runs unconditionally, the same way nfsd and rpc_pipefs release
their keyed s_fs_info. That also stops ->put_super() from clearing s_fs_info while the superblock is still
on @fs_supers. generic_shutdown_super() leaves it there on purpose so that sget_fc() keeps finding it
until kill_sb() has run, but a NULL s_fs_info makes test_keyed_super() miss it, so a concurrent mount for
the same user namespace skips the grab_super() wait and creates a second superblock for a namespace that
is still being torn down. (CVE-2026-74483)

Solution

Update the sys-kernel/cchost-kernel-6_12 library and its related packages to version 19999.44.28 or later.

Plugin Details

Severity: Medium

ID: 471259

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: 23.62

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-2026-74483

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: 8/15/2026

Reference Information

CVE: CVE-2026-74483

Detections

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