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Unity Linux 20.1050a Security Update: kernel (UTSA-2026-100534)

high Nessus Plugin ID 336654

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-2026-100534 advisory.

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

 audit: Fix data races of skb_queue_len() readers on audit_queue

 Multiple readers access audit_queue.qlen via skb_queue_len() without holding the queue lock or using READ_ONCE(), while kauditd writes to this field via the skb_dequeue() __skb_unlink() path with WRITE_ONCE() protected by a spinlock. This constitutes data races.

 All affected skb_queue_len(&audit_queue) call sites:
 - kauditd_thread() wait_event_freezable() condition
 - audit_receive_msg() AUDIT_GET handler (s.backlog assignment)
 - audit_receive() backlog check
 - audit_log_start() backlog check and pr_warn()

 KCSAN reports the following conflicting access pattern (one example):
 ================================================================== BUG: KCSAN: data-race in audit_log_start / skb_dequeue

 write (marked) to 0xffffffff8512ee20 of 4 bytes by task 661 on cpu 57:
 skb_dequeue+0x70/0xf0 kauditd_send_queue+0x71/0x220 kauditd_thread+0x1cb/0x430 kthread+0x1c2/0x210 ret_from_fork+0x162/0x1a0 ret_from_fork_asm+0x1a/0x30

 read to 0xffffffff8512ee20 of 4 bytes by task 36586 on cpu 1:
 audit_log_start+0x2a0/0x6b0 audit_core_dumps+0x64/0xa0 do_coredump+0x14b/0x1260 get_signal+0xeb2/0xf70 arch_do_signal_or_restart+0x41/0x170 exit_to_user_mode_loop+0xa2/0x1c0 do_syscall_64+0x1a3/0x1c0 entry_SYSCALL_64_after_hwframe+0x76/0xe0

 value changed: 0x00000001 -> 0x00000000 ==================================================================

 Resolve the race by switching to lockless helper skb_queue_len_lockless(), which internally uses READ_ONCE() and properly pairs with the WRITE_ONCE() write accesses already present on the writer side.

 [PM: line length tweak]

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

https://nvd.nist.gov/vuln/detail/CVE-2026-64435

http://www.nessus.org/u?4f963093

http://www.nessus.org/u?f5efaff8

Plugin Details

Severity: High

ID: 336654

File Name: unity_linux_UTSA-2026-100534.nasl

Version: 1.1

Type: Local

Published: 8/17/2026

Updated: 8/17/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.5

Percentile: 51.88

CVSS v2

Risk Factor: High

Base Score: 8.5

Temporal Score: 6.3

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

CVSS Score Source: CVE-2026-64435

CVSS v3

Risk Factor: High

Base Score: 8.2

Temporal Score: 7.1

Vector: CVSS:3.0/AV:N/AC:L/PR:N/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: 8/13/2026

Vulnerability Publication Date: 7/23/2026

Reference Information

CVE: CVE-2026-64435