#VU23780 Permissions, Privileges, and Access Controls in shadow - CVE-2019-19882

Vulnerability identifier: #VU23780

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2019-19882

CWE-ID: CWE-264

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
shadow
Universal components / Libraries / Libraries used by multiple products

Vendor: Mark Florian

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to missconfigured setuid programs in shadow 4.8 when compiled using --with-libpam but without explicitly passing --disable-account-tools-setuid, and without a PAM configuration suitable for use with setuid account management tools.. A local unprivileged user can leverage groupadd, groupdel, groupmod, useradd, userdel, or usermod management tools to escalate privileges on the system to root.

The issue affects at least Gentoo, Arch Linux, and Void Linux.

Mitigation
Install update from vendor's website.

Vulnerable software versions

shadow: 4.8

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External links
https://bugs.archlinux.org/task/64836
https://bugs.gentoo.org/702252
https://github.com/shadow-maint/shadow/commit/edf7547ad5aa650be868cf2dac58944773c12d75
https://github.com/shadow-maint/shadow/pull/199
https://github.com/void-linux/void-packages/pull/17580

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.