Authorization bypass in zsh

Published: 2018-09-08

Risk	Low
Patch available	YES
Number of vulnerabilities	2
CVE-ID	CVE-2018-13259 CVE-2018-0502
CWE-ID	CWE-862
Exploitation vector	Local
Public exploit	Public exploit code for vulnerability #1 is available. Public exploit code for vulnerability #2 is available.
Vulnerable software Subscribe	zsh Client/Desktop applications / Software for system administration
Vendor	SourceForge

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Authorization bypass

EUVDB-ID: #VU14701

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 - Missing Authorization

Exploit availability: No

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

External links

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

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.

2) Authorization bypass

EUVDB-ID: #VU14702