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Unity Linux 20.1050e Security Update: kernel (UTSA-2026-006807)

high Nessus Plugin ID 305540

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-2026-006807 advisory.

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

 efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare

 Observed on kernel 6.6 (present on master as well):

 BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0 Call trace:
 kasan_check_range+0xe8/0x190
 __asan_loadN+0x1c/0x28 memcmp+0x98/0xd0 efivarfs_d_compare+0x68/0xd8
 __d_lookup_rcu_op_compare+0x178/0x218
 __d_lookup_rcu+0x1f8/0x228 d_alloc_parallel+0x150/0x648 lookup_open.isra.0+0x5f0/0x8d0 open_last_lookups+0x264/0x828 path_openat+0x130/0x3f8 do_filp_open+0x114/0x248 do_sys_openat2+0x340/0x3c0
 __arm64_sys_openat+0x120/0x1a0

 If dentry->d_name.len < EFI_VARIABLE_GUID_LEN , 'guid' can become negative, leadings to oob. The issue can be triggered by parallel lookups using invalid filename:

 T1 T2 lookup_open
 ->lookup simple_lookup d_add // invalid dentry is added to hash list

 lookup_open d_alloc_parallel
 __d_lookup_rcu
 __d_lookup_rcu_op_compare hlist_bl_for_each_entry_rcu // invalid dentry can be retrieved
 ->d_compare efivarfs_d_compare // oob

 Fix it by checking 'guid' before cmp.

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?4b82746f

http://www.nessus.org/u?c63bd466

https://nvd.nist.gov/vuln/detail/CVE-2025-39817

Plugin Details

Severity: High

ID: 305540

File Name: unity_linux_UTSA-2026-006807.nasl

Version: 1.1

Type: Local

Published: 4/8/2026

Updated: 4/8/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.0

CVSS v2

Risk Factor: Medium

Base Score: 6.2

Temporal Score: 4.6

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

CVSS Score Source: CVE-2025-39817

CVSS v3

Risk Factor: High

Base Score: 7.1

Temporal Score: 6.2

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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: 9/16/2025

Reference Information

CVE: CVE-2025-39817