Vulnerability · Published Aug 11, 2026 · Assigned by redhat
CVE-2026-72693Kbd: local privilege escalation in openvt via incorrect process owner verification allowing passwordless root login
High 7.8
In plain English
A high-severity improper access control in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | kbd | 2.6.4-8.el10_2 | ALSA-2026:57597 |
| AlmaLinux:8 | kbd | 2.0.4-11.el8_10.1 | ALSA-2026:78951 |
| AlmaLinux:9 | kbd | 2.4.0-12.el9_8 | ALSA-2026:57610 |
| AlmaLinux:10 | kbd-legacy | 2.6.4-8.el10_2 | ALSA-2026:57597 |
| AlmaLinux:8 | kbd-legacy | 2.0.4-11.el8_10.1 | ALSA-2026:78951 |
| AlmaLinux:9 | kbd-legacy | 2.4.0-12.el9_8 | ALSA-2026:57610 |
| AlmaLinux:10 | kbd-misc | 2.6.4-8.el10_2 | ALSA-2026:57597 |
| AlmaLinux:8 | kbd-misc | 2.0.4-11.el8_10.1 | ALSA-2026:78951 |
| AlmaLinux:9 | kbd-misc | 2.4.0-12.el9_8 | ALSA-2026:57610 |
| Debian:12 | kbd | no fix listed | DEBIAN-CVE-2026-72693 |
| Debian:13 | kbd | no fix listed | DEBIAN-CVE-2026-72693 |
| Debian:14 | kbd | 2.10.0-1 | DEBIAN-CVE-2026-72693 |
| Rocky Linux:10 | kbd | 0:2.6.4-8.el10_2 | RLSA-2026:57597 |
| Rocky Linux:8 | kbd | 0:2.0.4-11.el8_10.1 | RLSA-2026:78951 |
| Rocky Linux:9 | kbd | 0:2.4.0-12.el9_8 | RLSA-2026:57610 |
| Ubuntu:22.04:LTS | kbd | no fix listed | UBUNTU-CVE-2026-72693 |
| Ubuntu:24.04:LTS | kbd | no fix listed | UBUNTU-CVE-2026-72693 |
| Ubuntu:26.04:LTS | kbd | no fix listed | UBUNTU-CVE-2026-72693 |
| Ubuntu:26.10 | kbd | no fix listed | UBUNTU-CVE-2026-72693 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4.22 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4.22 | see references |
| Red Hat | Red Hat Hardened Images | see references |
| Red Hat | Red Hat Enterprise Linux 6 | see references |
| Red Hat | Red Hat Enterprise Linux 7 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
| Red Hat | Red Hat OpenShift Container Platform 5 | see references |
Weakness: CWE-284 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- RHSA-2026:41136 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:57597 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:57610 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:60440 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:66357 vendor-advisory, x_refsource_REDHAT
- RHSA-2026:78951 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-72693 vdb-entry, x_refsource_REDHAT
- RHBZ#2462115 issue-tracking, x_refsource_REDHAT