Vulnerability identifier: #VU14701

Vulnerability risk: Low

CVSSv3.1: 7 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2018-13259

CWE-ID: CWE-862

Exploitation vector: Local

Exploit availability: No

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

Vendor: SourceForge

Description

The vulnerability allows a local attacker to execute a program without proper authorization on the target system.

The vulnerability exists due to improper truncating of shebang (#!) lines that exceed 64 characters. A local attacker can access the shell and submit a shebang line longer than 64 characters, cause the software to make an execve() call to a program name that is a substring of the intended one and execute a program without proper authorization on the system.

Mitigation
Update to version 5.6.

Vulnerable software versions

zsh: 5.0.0 - 5.5.1

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External links
http://sourceforge.net/p/zsh/code/ci/1c4c7b6a4d17294df028322b70c53803a402233d

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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. However, proof of concept for this vulnerability is available.