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 19999.44.106

critical Tenable Cloud Security Plugin ID 475574

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: nfsd: don't free session slots that
are still in use nfsd4_sequence() can free the very slot it is currently processing. When the session
shrinker has reduced se_target_maxslots below se_fchannel.maxreqs, the shrink path checks three conditions
before calling free_session_slots(): 1. se_target_maxslots < maxreqs (shrink was advertised) 2.
slot->sl_generation == se_slot_gen (slot is up-to-date) 3. seq->maxslots <= se_target_maxslots (client
acknowledges) However, seq->slotid is never checked against se_target_maxslots. A client using a slot in
the range [se_target_maxslots, maxreqs) can satisfy all three conditions: its slot has the current
generation (set by a prior SEQUENCE), and it sends sa_highest_slotid <= se_target_maxslots to acknowledge
the reduction. free_session_slots() then kfrees every slot at index >= se_target_maxslots, including the
caller's own slot. The function continues to write sl_seqid, sl_flags, sl_generation, and stores the
dangling pointer in cstate->slot. Later, nfsd4_store_cache_entry() copies up to maxresp_cached bytes of
the compound reply into the freed sl_data[] array, corrupting whatever slab object now occupies that
address. Additionally, a concurrent thread processing SEQUENCE on a different high-numbered slot can have
its slot freed out from under it. NFSD4_SLOT_INUSE is set under nn->client_lock before the lock is
released, so any concurrent thread past SEQUENCE will have its slot marked. However, free_session_slots()
does not check NFSD4_SLOT_INUSE before freeing. Fix both problems by: 1. Checking that the current
request's slotid is below the shrink boundary. 2. Scanning slots in the to-be-freed range for
NFSD4_SLOT_INUSE and deferring the shrink if any are active. (CVE-2026-89689)

Solution

Update the sys-kernel/cchost-kernel-6_18 library and its related packages to version 19999.44.106 or later.

Plugin Details

Severity: Critical

ID: 475574

Version: Revision 1.1

Type: Local

Family: Google COS Security Checks

Published: 10/16/2026

Updated: 10/16/2026

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 58.42

Vendor

Vendor Severity: LOW

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.4

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

CVSS Score Source: CVE-2026-89689

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/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: 9/11/2026

Reference Information

CVE: CVE-2026-89689

Detections

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