High

Kbd: local privilege escalation in openvt via incorrect process owner verification allowing passwordless root login

Type: advisorySource: Official CVE List1 source record

`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//fd/0")`. `stat()` on `/proc//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.

Announced 11 Aug 2026Group revision 1

Original source ↗

CVE-2026-72693

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-72693

Red Hat Enterprise Linux 10

Source reference: /containers/cna/affected/0/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Red Hat Enterprise Linux 8

Source reference: /containers/cna/affected/1/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Red Hat Enterprise Linux 9

Source reference: /containers/cna/affected/2/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Red Hat OpenShift Container Platform 4.22

Source reference: /containers/cna/affected/3/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Red Hat OpenShift Container Platform 4.22

Source reference: /containers/cna/affected/4/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Red Hat Hardened Images

Source reference: /containers/cna/affected/5/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Red Hat Enterprise Linux 6

Source reference: /containers/cna/affected/6/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Red Hat Enterprise Linux 7

Source reference: /containers/cna/affected/7/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Red Hat OpenShift Container Platform 4

Source reference: /containers/cna/affected/8/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:10.2"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 10",
    "versions": [
      {
        "status": "unaffected",
        "version": "0:2.6.4-8.el10_2",
        "lessThan": "*",
        "versionType": "rpm"
      }
    ],
    "packageName": "kbd",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:8::baseos"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 8",
    "versions": [
      {
        "status": "unaffected",
        "version": "0:2.0.4-11.el8_10.1",
        "lessThan": "*",
        "versionType": "rpm"
      }
    ],
    "packageName": "kbd",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:9::baseos"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 9",
    "versions": [
      {
        "status": "unaffected",
        "version": "0:2.4.0-12.el9_8",
        "lessThan": "*",
        "versionType": "rpm"
      }
    ],
    "packageName": "kbd",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/a:redhat:openshift:4.22::el9"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat OpenShift Container Platform 4.22",
    "versions": [
      {
        "status": "unaffected",
        "version": "4.22.9.8.202608251819-0",
        "lessThan": "*",
        "versionType": "rpm"
      }
    ],
    "packageName": "openshift/ose-rhel-coreos-9",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/a:redhat:openshift:4.22::el9"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat OpenShift Container Platform 4.22",
    "versions": [
      {
        "status": "unaffected",
        "version": "4.22.9.8.202609081748-0",
        "lessThan": "*",
        "versionType": "rpm"
      }
    ],
    "packageName": "openshift/ose-rhel-coreos-9",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/a:redhat:hummingbird:1"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Hardened Images",
    "versions": [
      {
        "status": "unaffected",
        "version": "2.10.0-2.hum1",
        "lessThan": "*",
        "versionType": "rpm"
      }
    ],
    "packageName": "kbd-main",
    "collectionURL": "https://catalog.redhat.com/software/containers/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:6"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 6",
    "packageName": "kbd",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "unknown"
  },
  {
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:7"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat Enterprise Linux 7",
    "packageName": "kbd",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  },
  {
    "cpes": [
      "cpe:/a:redhat:openshift:4"
    ],
    "vendor": "Red Hat",
    "product": "Red Hat OpenShift Container Platform 4",
    "packageName": "openshift/ose-rhel-coreos-8",
    "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
    "defaultStatus": "affected"
  }
]

Related CVEs: CVE-2026-72693
Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event: #16166 · Revision 1
Added to Heist Feed: Sun, 25 Oct 2026 01:12:24 GMT
Publisher date: Tue, 11 Aug 2026 08:39:24 GMT

Read the original announcement

Revision history

25 Oct 2026CVE-2026-72693 · Revision 1Source updated