7.8 CVE-2026-72693

Enriched by CISA Local Execution Code
 

`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.
https://nvd.nist.gov/vuln/detail/CVE-2026-72693

Categories

CWE-284 : Improper Access Control
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. The terms "access control" and "authorization" are often used interchangeably, although many people have distinct definitions. The CWE usage of "access control" is intended as a general term for the various mechanisms that restrict which users can access which resources, and "authorization" is more narrowly defined. It is unlikely that there will be community consensus on the use of these terms. Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software. Chain: IPSec VPN product uses the same variable for multiple purposes in the same function (CWE-1109), leading to incorrect access control (CWE-284) and expired pointer dereference (CWE-825) A form hosting website only checks the session authentication status for a single form, making it possible to bypass authentication when there are multiple forms Access-control setting in web-based document collaboration tool is not properly implemented by the code, which prevents listing hidden directories but does not prevent direct requests to files in those directories. Python-based HTTP library did not scope cookies to a particular domain such that "supercookies" could be sent to any domain on redirect Chain: Cloud computing virtualization platform does not require authentication for upload of a tar format file (CWE-306), then uses .. path traversal sequences (CWE-23) in the file to access unexpected files, as exploited in the wild per CISA KEV. IT management product does not perform authentication for some REST API requests, as exploited in the wild per CISA KEV. Firmware for a WiFi router uses a hard-coded password for a BusyBox shell, allowing bypass of authentication through the UART port Bluetooth speaker does not require authentication for the debug functionality on the UART port, allowing root shell access Default setting in workflow management product allows all API requests without authentication, as exploited in the wild per CISA KEV. Bulletin board applies restrictions on number of images during post creation, but does not enforce this on editing.

References


 

AFFECTED (from MITRE)


Vendor Product Versions
Red Hat Red Hat Enterprise Linux 10
  • 0:2.6.4-8.el10_2 < * [unaffected]
Red Hat Red Hat Enterprise Linux 9
  • 0:2.4.0-12.el9_8 < * [unaffected]
Red Hat Red Hat Hardened Images
  • 2.10.0-2.hum1 < * [unaffected]
Red Hat Red Hat Enterprise Linux 6
    Red Hat Red Hat Enterprise Linux 7
      Red Hat Red Hat Enterprise Linux 8
        Red Hat Red Hat OpenShift Container Platform 4
          © 2022 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation.

          CPE

          cpe start end


          REMEDIATION




          EXPLOITS


          Exploit-db.com

          id description date
          No known exploits

          POC Github

          Url
          No known exploits

          Other Nist (github, ...)

          Url
          No known exploits


          CAPEC


          Common Attack Pattern Enumerations and Classifications

          id description severity
          19 Embedding Scripts within Scripts
          High
          441 Malicious Logic Insertion
          High
          478 Modification of Windows Service Configuration
          High
          479 Malicious Root Certificate
          Low
          502 Intent Spoof
          503 WebView Exposure
          536 Data Injected During Configuration
          High
          546 Incomplete Data Deletion in a Multi-Tenant Environment
          Medium
          550 Install New Service
          551 Modify Existing Service
          552 Install Rootkit
          High
          556 Replace File Extension Handlers
          558 Replace Trusted Executable
          High
          562 Modify Shared File
          563 Add Malicious File to Shared Webroot
          564 Run Software at Logon
          578 Disable Security Software
          Medium


          MITRE


          Techniques

          id description
          T1014 Rootkit
          T1027.009 Obfuscated Files or Information: Embedded Payloads
          T1037 Boot or Logon Initialization Scripts
          T1080 Taint shared content
          T1505.005 Server Software Component: Terminal Services DLL
          T1542.003 Pre-OS Boot:Bootkit
          T1543 Create or Modify System Process
          T1543.001 Create or Modify System Process: Launch Agent
          T1543.003 Create or Modify System Process:Windows Service
          T1543.004 Create or Modify System Process: Launch Daemon
          T1546.001 Event Triggered Execution:Change Default File Association
          T1546.004 Event Triggered Execution:.bash_profile and .bashrc
          T1546.008 Event Triggered Execution: Accessibility Features
          T1546.016 Event Triggered Execution: Installer Packages
          T1547 Boot or Logon Autostart Execution
          T1547.006 Boot or Logon Autostart Execution:Kernel Modules and Extensions
          T1553.004 Subvert Trust Controls:Install Root Certificate
          T1556.006 Modify Authentication Process: Multi-Factor Authentication
          T1562.001 Impair Defenses: Disable or Modify Tools
          T1562.002 Impair Defenses: Disable Windows Event Logging
          T1562.004 Impair Defenses: Disable or Modify System Firewall
          T1562.007 Impair Defenses: Disable or Modify Cloud Firewall
          T1562.008 Impair Defenses: Disable Cloud Logs
          T1562.009 Impair Defenses: Safe Mode Boot
          T1574.011 Hijack Execution Flow:Service Registry Permissions Weakness
          © 2022 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation.

          Mitigations

          id description
          M1040 On Windows 10, enable Attack Surface Reduction (ASR) rules to prevent execution of potentially obfuscated scripts.
          M1024 Ensure proper permissions are set for Registry hives to prevent users from modifying keys for logon scripts that may lead to persistence.
          M1022 Protect shared folders by minimizing users who have write access.
          M1024 Consider using Group Policy to configure and block modifications to Terminal Services parameters in the Registry.
          M1026 Ensure proper permissions are in place to help prevent adversary access to privileged accounts necessary to install a bootkit.
          M1018 Limit privileges of user accounts and groups so that only authorized administrators can interact with system-level process changes and service configurations.
          M1022 Set group policies to restrict file permissions to the <code>~/launchagents</code> folder.
          M1018 Limit privileges of user accounts and groups so that only authorized administrators can interact with service changes and service configurations.
          M1018 Limit privileges of user accounts and remediate Privilege Escalation vectors so only authorized administrators can create new Launch Daemons.
          M1022 Making these files immutable and only changeable by certain administrators will limit the ability for adversaries to easily create user level persistence.
          M1028 To use this technique remotely, an adversary must use it in conjunction with RDP. Ensure that Network Level Authentication is enabled to force the remote desktop session to authenticate before the session is created and the login screen displayed. It is enabled by default on Windows Vista and later.
          M1018 Use MDM to disable user's ability to install or approve kernel extensions, and ensure all approved kernel extensions are in alignment with policies specified in <code>com.apple.syspolicy.kernel-extension-policy</code>.
          M1054 HTTP Public Key Pinning (HPKP) is one method to mitigate potential Adversary-in-the-Middle situations where and adversary uses a mis-issued or fraudulent certificate to intercept encrypted communications by enforcing use of an expected certificate.
          M1018 Ensure that proper policies are implemented to dictate the secure enrollment and deactivation of MFA for user accounts.
          M1018 Ensure proper user permissions are in place to prevent adversaries from disabling or interfering with security services.
          M1018 Ensure proper user permissions are in place to prevent adversaries from disabling or interfering with logging.
          M1018 Ensure proper user permissions are in place to prevent adversaries from disabling or modifying firewall settings.
          M1018 Ensure least privilege principles are applied to Identity and Access Management (IAM) security policies.
          M1018 Configure default account policy to enable logging. Manage policies to ensure only necessary users have permissions to make changes to logging policies.
          M1054 Ensure that endpoint defenses run in safe mode.
          M1024 Ensure proper permissions are set for Registry hives to prevent users from modifying keys for system components that may lead to privilege escalation.
          © 2022 The MITRE Corporation. Esta obra se reproduce y distribuye con el permiso de The MITRE Corporation.