Google: sys-kernel/cchost-kernel-6_12, sys-kernel/csql-kernel-6_12, sys-kernel/csql-kernel-6_6, sys-kernel/lakitu-kernel-6_12, sys-kernel/lakitu-kernel-6_6, sys-kernel/lakitu-nc-kernel-6_12, sys-kernel/lakitu-nc-kernel-6_6, sys-kernel/lakitu-vgpu-kernel-6_6: security update to 19216.395.4

medium Tenable Self-Hosted Container Security Plugin ID 469225

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: hwrng: core - use RCU and work_struct
to fix race condition Currently, hwrng_fill is not cleared until the hwrng_fillfn() thread exits. Since
hwrng_unregister() reads hwrng_fill outside the rng_mutex lock, a concurrent hwrng_unregister() may call
kthread_stop() again on the same task. Additionally, if hwrng_unregister() is called immediately after
hwrng_register(), the stopped thread may have never been executed. Thus, hwrng_fill remains dirty even
after hwrng_unregister() returns. In this case, subsequent calls to hwrng_register() will fail to start
new threads, and hwrng_unregister() will call kthread_stop() on the same freed task. In both cases, a use-
after-free occurs: refcount_t: addition on 0; use-after-free. WARNING: ... at lib/refcount.c:25
refcount_warn_saturate+0xec/0x1c0 Call Trace: kthread_stop+0x181/0x360 hwrng_unregister+0x288/0x380
virtrng_remove+0xe3/0x200 This patch fixes the race by protecting the global hwrng_fill pointer inside the
rng_mutex lock, so that hwrng_fillfn() thread is stopped only once, and calls to kthread_run() and
kthread_stop() are serialized with the lock held. To avoid deadlock in hwrng_fillfn() while being stopped
with the lock held, we convert current_rng to RCU, so that get_current_rng() can read current_rng without
holding the lock. To remove the lock from put_rng(), we also delay the actual cleanup into a work_struct.
Since get_current_rng() no longer returns ERR_PTR values, the IS_ERR() checks are removed from its
callers. With hwrng_fill protected by the rng_mutex lock, hwrng_fillfn() can no longer clear hwrng_fill
itself. Therefore, if hwrng_fillfn() returns directly after current_rng is dropped, kthread_stop() would
be called on a freed task_struct later. To fix this, hwrng_fillfn() calls schedule() now to keep the task
alive until being stopped. The kthread_stop() call is also moved from hwrng_unregister() to
drop_current_rng(), ensuring kthread_stop() is called on all possible paths where current_rng becomes
NULL, so that the thread would not wait forever. (CVE-2026-45949)

Solution

Update the sys-kernel/cchost-kernel-6_12 library and its related packages to version 19216.395.4 or later.

Plugin Details

Severity: Medium

ID: 469225

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: Low

Score: 3

Percentile: 23.75

Vendor

Vendor Severity: LOW

CVSS v2

Risk Factor: Low

Base Score: 3.8

Temporal Score: 2.8

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

CVSS Score Source: CVE-2026-45949

CVSS v3

Risk Factor: Medium

Base Score: 4.7

Temporal Score: 4.1

Vector: CVSS:3.0/AV:L/AC:H/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: 3/27/2026

Reference Information

CVE: CVE-2026-45949

Detections

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