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Unity Linux 20.1050e Security Update: kernel (UTSA-2026-006728)

high Nessus Plugin ID 305477

Synopsis

The Unity Linux host is missing one or more security updates.

Description

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2026-006728 advisory.

 In the Linux kernel, the following vulnerability has been resolved:

 cifs: Fix UAF in cifs_demultiplex_thread()

 There is a UAF when xfstests on cifs:

 BUG: KASAN: use-after-free in smb2_is_network_name_deleted+0x27/0x160 Read of size 4 at addr ffff88810103fc08 by task cifsd/923

 CPU: 1 PID: 923 Comm: cifsd Not tainted 6.1.0-rc4+ #45 ...
 Call Trace:
 <TASK> dump_stack_lvl+0x34/0x44 print_report+0x171/0x472 kasan_report+0xad/0x130 kasan_check_range+0x145/0x1a0 smb2_is_network_name_deleted+0x27/0x160 cifs_demultiplex_thread.cold+0x172/0x5a4 kthread+0x165/0x1a0 ret_from_fork+0x1f/0x30 </TASK>

 Allocated by task 923:
 kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30
 __kasan_slab_alloc+0x54/0x60 kmem_cache_alloc+0x147/0x320 mempool_alloc+0xe1/0x260 cifs_small_buf_get+0x24/0x60 allocate_buffers+0xa1/0x1c0 cifs_demultiplex_thread+0x199/0x10d0 kthread+0x165/0x1a0 ret_from_fork+0x1f/0x30

 Freed by task 921:
 kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 kasan_save_free_info+0x2a/0x40
 ____kasan_slab_free+0x143/0x1b0 kmem_cache_free+0xe3/0x4d0 cifs_small_buf_release+0x29/0x90 SMB2_negotiate+0x8b7/0x1c60 smb2_negotiate+0x51/0x70 cifs_negotiate_protocol+0xf0/0x160 cifs_get_smb_ses+0x5fa/0x13c0 mount_get_conns+0x7a/0x750 cifs_mount+0x103/0xd00 cifs_smb3_do_mount+0x1dd/0xcb0 smb3_get_tree+0x1d5/0x300 vfs_get_tree+0x41/0xf0 path_mount+0x9b3/0xdd0
 __x64_sys_mount+0x190/0x1d0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0

 The UAF is because:

 mount(pid: 921) | cifsd(pid: 923)
 -------------------------------|------------------------------- | cifs_demultiplex_thread SMB2_negotiate | cifs_send_recv | compound_send_recv | smb_send_rqst | wait_for_response | wait_event_state [1] | | standard_receive3 | cifs_handle_standard | handle_mid | mid->resp_buf = buf; [2] | dequeue_mid [3] KILL the process [4] | resp_iov[i].iov_base = buf | free_rsp_buf [5] | | is_network_name_deleted [6] | callback

 1. After send request to server, wait the response until mid->mid_state != SUBMITTED;
 2. Receive response from server, and set it to mid;
 3. Set the mid state to RECEIVED;
 4. Kill the process, the mid state already RECEIVED, get 0;
 5. Handle and release the negotiate response;
 6. UAF.

 It can be easily reproduce with add some delay in [3] - [6].

 Only sync call has the problem since async call's callback is executed in cifsd process.

 Add an extra state to mark the mid state to READY before wakeup the waitter, then it can get the resp safely.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update the affected kernel package.

See Also

http://www.nessus.org/u?c562228c

https://nvd.nist.gov/vuln/detail/CVE-2023-52572

Plugin Details

Severity: High

ID: 305477

File Name: unity_linux_UTSA-2026-006728.nasl

Version: 1.1

Type: Local

Published: 4/8/2026

Updated: 4/8/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

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-2023-52572

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

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/UOS-Server/release, Host/UOS-Server/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 4/8/2026

Vulnerability Publication Date: 10/24/2023

Reference Information

CVE: CVE-2023-52572