#VU59358 Uncontrolled recursion in systemd - CVE-2021-3997

Vulnerability identifier: #VU59358

Vulnerability risk: Low

CVSSv4.0: 5.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:U/U:Clear]

CVE-ID: CVE-2021-3997

CWE-ID: CWE-674

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
systemd
Server applications / Other server solutions

Vendor: Freedesktop.org

Description

The vulnerability allows a local user to perform a denial of service (DoS) attack.

The vulnerability exists due to uncontrolled recursion in systemd-tmpfiles. A local user can create multiple nested directories in the /tmp folder and case systemd to crash during the system boot.

Mitigation
Install update from vendor's website.

Vulnerable software versions

systemd: 241 - 250.1

---

External links
https://seclists.org/oss-sec/2022/q1/18
https://github.com/systemd/systemd/commit/55a89ea1b4088a6d84ba0bd3cd8e648bd51f1ebf

---

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.