#VU49884 Link following in Sudo - CVE-2021-23240

Vulnerability identifier: #VU49884

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-2021-23240

CWE-ID: CWE-59

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Sudo
Client/Desktop applications / Software for system administration

Vendor: Sudo

Description

The vulnerability allows a local authenticated user to execute arbitrary code.

selinux_edit_copy_tfiles in sudoedit in Sudo before 1.9.5 allows a local unprivileged user to gain file ownership and escalate privileges by replacing a temporary file with a symlink to an arbitrary file target. This affects SELinux RBAC support in permissive mode. Machines without SELinux are not vulnerable.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Sudo: 1.9.0 - 1.9.4p2

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External links
https://bugzilla.suse.com/show_bug.cgi?id=CVE-2021-23240
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/EE42Y35SMJOLONAIBNYNFC7J44UUZ2Y6/
https://www.sudo.ws/stable.html#1.9.5

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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.