RHEL 9 : krb5 (RHSA-2026:97456)

high Nessus Plugin ID 378201

Synopsis

The remote Red Hat host is missing one or more security updates for krb5.

Description

The remote Redhat Enterprise Linux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the RHSA-2026:97456 advisory.

Kerberos is a network authentication system, which can improve the security of your network by eliminating the insecure practice of sending passwords over the network in unencrypted form. It allows clients and servers to authenticate to each other with the help of a trusted third party, the Kerberos key distribution center (KDC).

Security Fix(es):

* krb5: MIT Kerberos 5 (krb5): Denial of Service via integer underflow and out-of-bounds read (CVE-2026-40356)

* krb5: MIT Kerberos 5: Denial of Service via NULL pointer dereference in NegoEx mechanism (CVE-2026-40355)

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.

Additional Changes:

For detailed information on changes in this release, see the Red Hat Enterprise Linux 9 Release Notes linked from 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 these issues but has instead relied only on the application's self-reported version number.

Solution

Update the RHEL krb5 package based on the guidance in RHSA-2026:97456.

Plugin Details

Severity: High

ID: 378201

File Name: redhat-RHSA-2026-97456.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Red Hat Local Security Checks

Published: 11/10/2026

Updated: 11/10/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 92.8

Vendor

Vendor Severity: Moderate

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.1

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

CVSS Score Source: CVE-2026-40356

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.7

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

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

Vulnerability Information

CPE: cpe:/o:redhat:enterprise_linux:9, p-cpe:/a:redhat:enterprise_linux:krb5-devel, p-cpe:/a:redhat:enterprise_linux:krb5-libs, p-cpe:/a:redhat:enterprise_linux:krb5-pkinit, p-cpe:/a:redhat:enterprise_linux:krb5-server-ldap, p-cpe:/a:redhat:enterprise_linux:krb5-server, p-cpe:/a:redhat:enterprise_linux:krb5-workstation, p-cpe:/a:redhat:enterprise_linux:krb5, p-cpe:/a:redhat:enterprise_linux:libkadm5

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 11/10/2026

Vulnerability Publication Date: 4/28/2026

Reference Information

CVE: CVE-2026-40355, CVE-2026-40356

CWE: 191, 476

RHSA: 2026:97456

Detections

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