Remote command execution in zsh

1) OS Command Injection

EUVDB-ID: #VU60674

Risk: High

CVSSv3.1: 7.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-45444

CWE-ID: CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary shell commands on the target system.

The vulnerability exists due to recursive PROMPT_SUBST expansion when processing malicious output. A remote attacker with ability to control the output can inject and execute arbitrary commands on the system with privileges on the current user.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

zsh: 5.0.0 - 5.8

External links

http://zsh.sourceforge.io/releases.html
http://vuln.ryotak.me/advisories/63
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2P3LPMGENEHKDWFO4MWMZSZL6G7Y4CV7/
http://www.debian.org/security/2022/dsa-5078

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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