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CentOS Linux 7 [TuxCare] Security Update: kbd / kbd-legacy / kbd-misc (CENTOS7:CLSA-2026:1793289377)

high Nessus Plugin ID 375246

Synopsis

The CentOS Linux host is missing one or more security updates.

Description

The CentOS Linux 7 host has packages installed that are affected by a vulnerability as referenced in the TuxCare CENTOS7:CLSA-2026:1793289377 advisory.

 - `openvt -u` is intended to identify the owner of the current VT and then execute `login` as that user from a privileged context. In the documented `kbrequest`/init usage, the ownership test in `authenticate_user()` relies on `stat(/proc/<pid>/fd/0)`. `stat()` on `/proc/<pid>/fd/0` follows the symlink to the underlying TTY device node. As a result, `buf.st_uid` reflects the owner of the TTY node rather than the owner of the process holding the file descriptor. If the TTY owner returns to `root` or the getty owner after logout while an unprivileged process still has `fd 0` attached to that TTY, the check can incorrectly treat that process as belonging to the privileged console owner. Once that check succeeds, the `-u` path executes a passwordless login as the selected user. In the documented `kbrequest`/init deployment using `openvt -us`, this can result in passwordless `login -f root` on the spawned VT. This report establishes that privilege escalation path for that documented deployment; it does not claim equivalent reachability for deployments that do not use `openvt -u` from a privileged `kbrequest`/init path. (CVE-2026-72693)

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 packages based on the guidance in TuxCare advisory CENTOS7:CLSA-2026:1793289377.

See Also

https://cve.tuxcare.com/els/releases/CLSA-2026:1793289377

http://www.nessus.org/u?bf81d120

Plugin Details

Severity: High

ID: 375246

File Name: tuxcare_centos_7_CLSA-2026-1793289377.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 11/2/2026

Updated: 11/2/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 58.16

Vendor

Vendor Severity: Important

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

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

CVSS Score Source: CVE-2026-72693

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

Vector: CVSS:3.0/AV:L/AC:L/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/CentOS/release, Host/CentOS/rpm-list, Host/OS/extended-third-party

Exploit Ease: No known exploits are available

Patch Publication Date: 10/29/2026

Vulnerability Publication Date: 8/11/2026

Reference Information

CVE: CVE-2026-72693

CLSA: 2026:1793289377