CVE-2019-19234
Description
When an account is disabled via the shadow file, by replacing the password hash with "!", it is not considered disabled by sudo. And depending on the configuration, sudo can be run by using such disabled account.
Statement
The new runas_check_shell sudoers setting can be used to require that the runas user have a shell listed in the /etc/shells file. On many systems, users such as bin, do not have a valid shell and this flag can be used to prevent commands from being run as those users.
Mitigation
This flaw basically allows users which have disabled account in /etc/shadow (password is replaced with '!) to have sudo access. Systems not having such disabled account, or systems disabling sudo access for such accounts using other means (such as not allowing such users to run sudo via access control mechanisms) are not affected by this flaw.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | 7.5 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Understanding the Weakness (CWE)
Other
Technical Impact: Varies by Context
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