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RHEL 7 : kernel-rt (RHSA-2026:78843)

high Nessus Plugin ID 364153

Synopsis

The remote Red Hat host is missing a security update for kernel-rt.

Description

The remote Redhat Enterprise Linux 7 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2026:78843 advisory.

 The kernel-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements.

 Security Fix(es):

 * kernel: KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O (CVE-2025-40026)

 For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise 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 RHEL kernel-rt package based on the guidance in RHSA-2026:78843.

See Also

https://access.redhat.com/errata/RHSA-2026:78843

https://access.redhat.com/security/updates/classification/#moderate

https://bugzilla.redhat.com/show_bug.cgi?id=2406712

http://www.nessus.org/u?2b7a3cc0

Plugin Details

Severity: High

ID: 364153

File Name: redhat-RHSA-2026-78843.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 10/8/2026

Updated: 10/8/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

Percentile: 57.55

Vendor

Vendor Severity: Moderate

CVSS v2

Risk Factor: Medium

Base Score: 5.7

Temporal Score: 4.2

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

CVSS Score Source: CVE-2025-40026

CVSS v3

Risk Factor: High

Base Score: 7.9

Temporal Score: 6.9

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:redhat:enterprise_linux:7, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug, p-cpe:/a:redhat:enterprise_linux:kernel-rt-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-doc, p-cpe:/a:redhat:enterprise_linux:kernel-rt-trace-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-trace, p-cpe:/a:redhat:enterprise_linux:kernel-rt

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

Exploit Ease: No known exploits are available

Patch Publication Date: 10/8/2026

Vulnerability Publication Date: 10/23/2025

Reference Information

CVE: CVE-2025-40026

CWE: 754

RHSA: 2026:78843