Google: sys-kernel/csql-kernel-6_1, sys-kernel/csql-kernel-6_6, sys-kernel/lakitu-kernel-6_1, sys-kernel/lakitu-kernel-6_6, sys-kernel/lakitu-nc-kernel-6_6, sys-kernel/lakitu-vgpu-kernel-6_6, sys-kernel/tpusev-kernel-6_6: security update to 18613.613.5

high Tenable Cloud Security Plugin ID 467032

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: blk-cgroup: fix use-after-free in
cgwb_release_workfn() cgwb_release_workfn() calls css_put(wb->blkcg_css) and then later accesses
wb->blkcg_css again via blkcg_unpin_online(). If css_put() drops the last reference, the blkcg can be
freed asynchronously (css_free_rwork_fn -> blkcg_css_free -> kfree) before blkcg_unpin_online()
dereferences the pointer to access blkcg->online_pin, resulting in a use-after-free: BUG: KASAN: slab-use-
after-free in blkcg_unpin_online (./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-
instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432
./include/linux/refcount.h:450 block/blk-cgroup.c:1367) Write of size 4 at addr ff11000117aa6160 by task
kworker/71:1/531 Workqueue: cgwb_release cgwb_release_workfn Call Trace: <TASK> blkcg_unpin_online
(./include/linux/instrumented.h:112 ./include/linux/atomic/atomic-instrumented.h:400
./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 block/blk-
cgroup.c:1367) cgwb_release_workfn (mm/backing-dev.c:629) process_scheduled_works (kernel/workqueue.c:3278
kernel/workqueue.c:3385) Freed by task 1016: kfree (./include/linux/kasan.h:235 mm/slub.c:2689
mm/slub.c:6246 mm/slub.c:6561) css_free_rwork_fn (kernel/cgroup/cgroup.c:5542) process_scheduled_works
(kernel/workqueue.c:3302 kernel/workqueue.c:3385) ** Stack based on commit 66672af7a095 ("Add linux-next
specific files for 20260410") I am seeing this crash sporadically in Meta fleet across multiple kernel
versions. A full reproducer is available at:
https://github.com/leitao/debug/blob/main/reproducers/repro_blkcg_uaf.sh (The race window is narrow. To
make it easily reproducible, inject a msleep(100) between css_put() and blkcg_unpin_online() in
cgwb_release_workfn(). With that delay and a KASAN-enabled kernel, the reproducer triggers the splat
reliably in less than a second.) Fix this by moving blkcg_unpin_online() before css_put(), so the cgwb's
CSS reference keeps the blkcg alive while blkcg_unpin_online() accesses it. (CVE-2026-31586)

Solution

Update the sys-kernel/csql-kernel-6_1 library and its related packages to version 18613.613.5 or later.

Plugin Details

Severity: High

ID: 467032

Version: Revision 1.3

Type: Local

Family: Google COS Security Checks

Published: 10/2/2026

Updated: 10/3/2026

Supported Sensors: Tenable Cloud Security, Tenable Self-Hosted Container Security

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 57.94

Vendor

Vendor Severity: LOW

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

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

CVSS Score Source: CVE-2026-31586

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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: 4/24/2026

Reference Information

CVE: CVE-2026-31586

Detections

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