5.4 CVE-2026-58092
In FreeBSD 15.0, the kernel structure used to represent user credentials changed: previously the primary group ID was stored in the first element of the array containing the list of supplementary group IDs, whereas now the primary group ID is stored in a dedicated field. This change was largely internal to the kernel and not user-visible.
One function, group_is_primary(), was not properly updated as a part of this transition. This function is used by mac_do to determine the primary group ID of the credential after applying a transition rule, used when the rule target does not explicitly specify a group.
As a result, with certain mac_do rules, it is possible for a credential switch to incorrectly set the primary group ID to the ID stored in the first element of the original credential's supplementary group array.
If the list of supplementary groups is empty, this value will be 0, corresponding to the "wheel" group. For example, a rule such as "uid=1001>uid=1002" can be abused to set the primary group ID to 0 even if the process did not originally belong to group 0.
Certain mac_do rules can be abused to set a process' group ID to 0. Note however, that the rule must apply to the caller in order for the bug to be triggered, e.g., given the ruleset "uid=1001>uid=1002", the user must have user ID 1001 in order to trigger the bug.
Further, logged-in users will in general have a non-empty supplementary group list, in which case the bug can at worst be used to set the credential's first supplementary group ID as its primary group ID. Processes must explicitly remove themselves from all supplementary groups, using the privileged setgroups(2) system call, in order to exploit the bug to set 0 as the primary group ID.
Since membership in group 0 is often used to enable controlled privilege escalation, the bug might be further exploitable to obtain root privileges, depending on the system configuration. For instance, a ruleset such as the following could be exploited by a process running as user 1001 and with an empty supplementary group list: "uid=1001>uid=1002;gid=0>uid=0".
https://nvd.nist.gov/vuln/detail/CVE-2026-58092
Categories
CWE-288 : Authentication Bypass Using an Alternate Path or Channel
The product requires authentication, but the product has an alternate path or channel that does not require authentication. Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource. Router allows remote attackers to read system logs without authentication by directly connecting to the login screen and typing certain control characters. Attackers with physical access to the machine may bypass the password prompt by pressing the ESC (Escape) key. OS allows local attackers to bypass the password protection of idled sessions via the programmer's switch or CMD-PWR keyboard sequence, which brings up a debugger that the attacker can use to disable the lock. Direct request of installation file allows attacker to create administrator accounts. Attackers may gain additional privileges by directly requesting the web management URL. Bypass authentication via direct request to named pipe. User can avoid lockouts by using an API instead of the GUI to conduct brute force password guessing.
References
AFFECTED (from MITRE)
| Vendor |
Product |
Versions |
| FreeBSD |
FreeBSD |
- 15.1-RELEASE < p3 [affected]
- 15.0-RELEASE < p13 [affected]
|
| © 2022 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. |
CPE
REMEDIATION
EXPLOITS
Exploit-db.com
| id |
description |
date |
|
| No known exploits |
POC Github
Other Nist (github, ...)
CAPEC
Common Attack Pattern Enumerations and Classifications
| id |
description |
severity |
| 127 |
Directory Indexing
An adversary crafts a request to a target that results in the target listing/indexing the content of a directory as output. One common method of triggering directory contents as output is to construct a request containing a path that terminates in a directory name rather than a file name since many applications are configured to provide a list of the directory's contents when such a request is received. An adversary can use this to explore the directory tree on a target as well as learn the names of files. This can often end up revealing test files, backup files, temporary files, hidden files, configuration files, user accounts, script contents, as well as naming conventions, all of which can be used by an attacker to mount additional attacks. [Directory Discovery] Use a method, either manual, scripted, or automated to discover the directories on the server by making requests for directories that may possibly exist. During this phase the adversary is less concerned with whether a directory can be accessed or indexed and more focused on simply discovering what directories do exist on the target. [Iteratively explore directory/file structures] The adversary attempts to access the discovered directories that allow access and may attempt to bypass server or application level ACLs by using manual or automated methods [Read directories or files which are not intended for public viewing.] The adversary attempts to access the discovered directories that allow access and may attempt to bypass server or application level ACLs by using manual or automated methods |
Medium |
| 665 |
Exploitation of Thunderbolt Protection Flaws
[Survey physical victim environment and potential Thunderbolt system targets] The adversary monitors the target's physical environment to identify systems with Thunderbolt interfaces, identify potential weaknesses in physical security in addition to periods of nonattendance by the victim over their Thunderbolt interface equipped devices, and when the devices are in locked or sleep state. [Evaluate the target system and its Thunderbolt interface] The adversary determines the device's operating system, Thunderbolt interface version, and any implemented Thunderbolt protections to plan the attack. [Obtain and/or clone firmware image] The adversary physically manipulates Thunderbolt enabled devices to acquire the firmware image from the target and/or adversary Thunderbolt host controller's SPI (Serial Peripheral Interface) flash. [Parse and locate relevant firmware data structures and information based upon Thunderbolt controller model, firmware version, and other information] The acquired victim and/or adversary firmware image is parsed for specific data and other relevant identifiers required for exploitation, based upon the victim device information and firmware version. [Disable Thunderbolt security and prevent future Thunderbolt security modifications (if necessary)] The adversary overrides the target device's Thunderbolt Security Level to "None" (SL0) and/or enables block protections upon the SPI flash to prevent the ability for the victim to perform and/or recognize future Thunderbolt security modifications as well as update the Thunderbolt firmware. [Modify/replace victim Thunderbolt firmware image] The modified victim and/or adversary thunderbolt firmware image is written to attacker SPI flash. [Connect adversary-controlled thunderbolt enabled device to victim device and verify successful execution of malicious actions] The adversary needs to determine if their exploitation of selected vulnerabilities had the intended effects upon victim device. [Exfiltration of desired data from victim device to adversary device] Utilize PCIe tunneling to transfer desired data and information from victim device across Thunderbolt connection. |
Very High |
MITRE
Techniques
| id |
description |
| T1083 |
File and Directory Discovery |
| T1211 |
Exploitation for Defensive Evasion |
| T1542.002 |
Pre-OS Boot:Component Firmware |
| T1556 |
Modify Authentication Process |
| © 2022 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. |
Mitigations
| id |
description |
| M1051 |
Update software regularly by employing patch management for internal enterprise endpoints and servers. |
| M1051 |
Perform regular firmware updates to mitigate risks of exploitation and/or abuse. |
| M1018 |
Ensure that proper policies are implemented to dictate the the secure enrollment and deactivation of authentication mechanisms, such as MFA, for user accounts. |
| © 2022 The MITRE Corporation. Esta obra se reproduce y distribuye con el permiso de The MITRE Corporation. |
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