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Unity Linux 20.1050e Security Update: kernel (UTSA-2026-007620)

medium Nessus Plugin ID 307179

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-2026-007620 advisory.

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

 net/9p: fix double req put in p9_fd_cancelled

 Syzkaller reports a KASAN issue as below:

 general protection fault, probably for non-canonical address 0xfbd59c0000000021: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: maybe wild-memory-access in range [0xdead000000000108-0xdead00000000010f] CPU: 0 PID: 5083 Comm: syz-executor.2 Not tainted 6.1.134-syzkaller-00037-g855bd1d7d838 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:__list_del include/linux/list.h:114 [inline] RIP: 0010:__list_del_entry include/linux/list.h:137 [inline] RIP: 0010:list_del include/linux/list.h:148 [inline] RIP: 0010:p9_fd_cancelled+0xe9/0x200 net/9p/trans_fd.c:734

 Call Trace:
 <TASK> p9_client_flush+0x351/0x440 net/9p/client.c:614 p9_client_rpc+0xb6b/0xc70 net/9p/client.c:734 p9_client_version net/9p/client.c:920 [inline] p9_client_create+0xb51/0x1240 net/9p/client.c:1027 v9fs_session_init+0x1f0/0x18f0 fs/9p/v9fs.c:408 v9fs_mount+0xba/0xcb0 fs/9p/vfs_super.c:126 legacy_get_tree+0x108/0x220 fs/fs_context.c:632 vfs_get_tree+0x8e/0x300 fs/super.c:1573 do_new_mount fs/namespace.c:3056 [inline] path_mount+0x6a6/0x1e90 fs/namespace.c:3386 do_mount fs/namespace.c:3399 [inline]
 __do_sys_mount fs/namespace.c:3607 [inline]
 __se_sys_mount fs/namespace.c:3584 [inline]
 __x64_sys_mount+0x283/0x300 fs/namespace.c:3584 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

 This happens because of a race condition between:

 - The 9p client sending an invalid flush request and later cleaning it up;
 - The 9p client in p9_read_work() canceled all pending requests.

 Thread 1 Thread 2 ...
 p9_client_create() ...
 p9_fd_create() ...
 p9_conn_create() ...
 // start Thread 2 INIT_WORK(&m->rq, p9_read_work);
 p9_read_work() ...
 p9_client_rpc() ...
 ...
 p9_conn_cancel() ...
 spin_lock(&m->req_lock);
 ...
 p9_fd_cancelled() ...
 ...
 spin_unlock(&m->req_lock);
 // status rewrite p9_client_cb(m->client, req, REQ_STATUS_ERROR) // first remove list_del(&req->req_list);
 ...

 spin_lock(&m->req_lock) ...
 // second remove list_del(&req->req_list);
 spin_unlock(&m->req_lock) ...

 Commit 74d6a5d56629 (9p/trans_fd: Fix concurrency del of req_list in p9_fd_cancelled/p9_read_work) fixes a concurrency issue in the 9p filesystem client where the req_list could be deleted simultaneously by both p9_read_work and p9_fd_cancelled functions, but for the case where req->status equals REQ_STATUS_RCVD.

 Update the check for req->status in p9_fd_cancelled to skip processing not just received requests, but anything that is not SENT, as whatever changed the state from SENT also removed the request from its list.

 Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

 [updated the check from status == RECV || status == ERROR to status != SENT]

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?44309631

http://www.nessus.org/u?1c6191ad

https://nvd.nist.gov/vuln/detail/CVE-2025-40027

Plugin Details

Severity: Medium

ID: 307179

File Name: unity_linux_UTSA-2026-007620.nasl

Version: 1.1

Type: Local

Published: 4/17/2026

Updated: 4/17/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: Medium

Base Score: 4.5

Temporal Score: 3.3

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

CVSS Score Source: CVE-2025-40027

CVSS v3

Risk Factor: Medium

Base Score: 5.3

Temporal Score: 4.6

Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/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: 4/17/2026

Vulnerability Publication Date: 10/23/2025

Reference Information

CVE: CVE-2025-40027