Unity Linux 20.1050e Security Update: kernel (UTSA-2026-007455)

high Nessus Plugin ID 307226

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-2026-007455 advisory.

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

fs/proc: fix uaf in proc_readdir_de()

Pde is erased from subdir rbtree through rb_erase(), but not set the node to EMPTY, which may result in uaf access. We should use RB_CLEAR_NODE() set the erased node to EMPTY, then pde_subdir_next() will return NULL to avoid uaf access.

We found an uaf issue while using stress-ng testing, need to run testcase getdent and tun in the same time. The steps of the issue is as follows:

1) use getdent to traverse dir /proc/pid/net/dev_snmp6/, and current pde is tun3;

2) in the [time windows] unregister netdevice tun3 and tun2, and erase them from rbtree. erase tun3 first, and then erase tun2. the pde(tun2) will be released to slab;

3) continue to getdent process, then pde_subdir_next() will return pde(tun2) which is released, it will case uaf access.

CPU 0 | CPU 1
------------------------------------------------------------------------- traverse dir /proc/pid/net/dev_snmp6/ | unregister_netdevice(tun->dev) //tun3 tun2 sys_getdents64() | iterate_dir() | proc_readdir() | proc_readdir_de() | snmp6_unregister_dev() pde_get(de); | proc_remove() read_unlock(&proc_subdir_lock); | remove_proc_subtree() | write_lock(&proc_subdir_lock);
[time window] | rb_erase(&root->subdir_node, &parent->subdir);
| write_unlock(&proc_subdir_lock);
read_lock(&proc_subdir_lock); | next = pde_subdir_next(de); | pde_put(de); | de = next; //UAF |

rbtree of dev_snmp6 | pde(tun3) / \ NULL pde(tun2)

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.

Plugin Details

Severity: High

ID: 307226

File Name: unity_linux_UTSA-2026-007455.nasl

Version: 1.1

Type: Local

Family: Unity Linux Local Security Checks

Published: 4/17/2026

Updated: 4/17/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Medium

Base Score: 6

Temporal Score: 4.4

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

CVSS Score Source: CVE-2025-40271

CVSS v3

Risk Factor: High

Base Score: 7

Temporal Score: 6.1

Vector: CVSS:3.0/AV:L/AC:H/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: 4/17/2026

Vulnerability Publication Date: 12/6/2025

Reference Information

CVE: CVE-2025-40271

Detections

Analytics