Google: sys-kernel/cchost-kernel-6_12, sys-kernel/csql-kernel-6_12, sys-kernel/lakitu-kernel-6_12, sys-kernel/lakitu-nc-kernel-6_12: security update to 19506.505.8

high Tenable Cloud Security Plugin ID 469289

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: ublk: clear VM_MAYWRITE on read-only
ublk char device mmap ublk_ch_mmap() rejects mmap requests with VM_WRITE set, but never clears VM_MAYWRITE
on the resulting read-only mapping. This allows a userspace daemon to mmap the per-queue command buffer
PROT_READ, then upgrade it to PROT_WRITE via mprotect(), since VM_MAYWRITE was never cleared. The command
buffer holds struct ublksrv_io_desc entries that are kernel-written ABI; a writable mapping lets an
unprivileged daemon process corrupt fields such as addr, op_flags, nr_sectors, and start_sector. Same bug
class as the drm/panthor and drm/vc4 VM_MAYWRITE fixes, and the 2026-08-13 ptp/vmclock fix (a5edadbae57e).
Verified via mprotect() PoC: before the fix, a PROT_READ mapping can be upgraded to PROT_READ|PROT_WRITE
and a write into the command buffer corrupts io_desc fields (confirmed under KASAN). After the fix,
mprotect() returns -EACCES. (CVE-2026-89793)

Solution

Update the sys-kernel/cchost-kernel-6_12 library and its related packages to version 19506.505.8 or later.

Plugin Details

Severity: High

ID: 469289

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: Medium

Score: 4.9

Percentile: 58.25

Vendor

Vendor Severity: HIGH

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-2026-89793

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: 9/16/2026

Reference Information

CVE: CVE-2026-89793

Detections

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