kbd privileges management

Summaryinfo

A vulnerability labeled as very critical has been found in kbd. The affected element is an unknown function. The manipulation results in privileges management. This vulnerability is known as CVE-2026-72693. Attacking locally is a requirement. No exploit is available.

Detailsinfo

A vulnerability, which was classified as very critical, was found in kbd (the affected version unknown). Affected is an unknown part. The manipulation with an unknown input leads to a privileges management vulnerability. CWE is classifying the issue as CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

`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.

This vulnerability is traded as CVE-2026-72693. The exploitability is told to be easy. The attack needs to be approached locally. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/24/2026). The MITRE ATT&CK project declares the attack technique as T1068.

The vulnerability scanner Nessus provides a plugin with the ID 339113 (MiracleLinux 9 : kbd-2.4.0-12.el9_8 (AXSA:2026-1640:01)), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Tenable (339113). Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

• kbd

CPE 2.3info

• 🔒

CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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