#VU14702 Authorization bypass in zsh - CVE-2018-0502

Vulnerability identifier: #VU14702

Vulnerability risk: Low

CVSSv4.0: 7.1 [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:P/U:Clear]

CVE-ID: CVE-2018-0502

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 handling of the beginning of a shebang (#!) script file. A local attacker can execute a shebang script file that submits malicious input, pass content from the second line of the file to execve() 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
https://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.