CVE-2026-72693: `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 `kb...

Description

`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.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.10%

1.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-284

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Red Hat	Red Hat Enterprise Linux 10	All versions
Red Hat	Red Hat Enterprise Linux 6	All versions
Red Hat	Red Hat Enterprise Linux 7	All versions
Red Hat	Red Hat Enterprise Linux 8	All versions
Red Hat	Red Hat Enterprise Linux 9	All versions
Red Hat	Red Hat Hardened Images	All versions
Red Hat	Red Hat OpenShift Container Platform 4	All versions

References

Timeline

Published: Aug 11, 2026
Last Modified: Aug 11, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-72693?

`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.

How severe is CVE-2026-72693?

CVE-2026-72693 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.10% probability of exploitation in the next 30 days.

How do I fix CVE-2026-72693?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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