SB2020022304 - Improper Check for Dropped Privileges in zsh (Alpine package)
Published: February 23, 2020
Security Bulletin ID
SB2020022304
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Local access
Highest impact
Code execution
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Improper Check for Dropped Privileges (CVE-ID: CVE-2019-20044)
CWE-ID: CWE-273 - Improper Check for Dropped Privileges
CVSSv4: 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
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to Zsh fails to overwrite the saved uid, so the original privileges, dropped by the --no-PRIVILEGED option, can be restored by
executing MODULE_PATH=/dir/with/module zmodload with a module that calls
setuid(). A local user can execute arbitrary commands on the system with elevated privileges.
Remediation
Install update from vendor's website.