Permissions, Privileges, and Access Controls in OpenBSD - CVE-2019-19726
Published: December 28, 2019 / Updated: June 17, 2021
Vulnerability identifier: #VU23831
CSH Severity: Low
CVSS v4.0: 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:A/U:Clear
CVE-ID: CVE-2019-19726
CWE-ID: CWE-264
Exploitation vector: Local access
Exploit availability:
Public exploit is available
Vendor: OpenBSD
Affected software:
OpenBSD
OpenBSD
Detailed vulnerability description
The vulnerability allows a local usre to escalate privileges on the system.
The vulnerability exists due to check for LD_LIBRARY_PATH in setuid programs can be defeated by setting a
very small RLIMIT_DATA resource limit. When executing chpass or passwd
(which are setuid root), _dl_setup_env in ld.so tries to strip
LD_LIBRARY_PATH from the environment, but fails when it cannot allocate
memory. A local user can execute arbitrary code on the system with root privileges.
How to mitigate CVE-2019-19726
Install updates from vendor's website.
Sources
- http://packetstormsecurity.com/files/155658/Qualys-Security-Advisory-OpenBSD-Dynamic-Loader-Privilege-Escalation.html
- http://packetstormsecurity.com/files/155764/OpenBSD-Dynamic-Loader-chpass-Privilege-Escalation.html
- http://seclists.org/fulldisclosure/2019/Dec/31
- https://seclists.org/bugtraq/2019/Dec/25
- https://www.openbsd.org/errata66.html
- https://www.openwall.com/lists/oss-security/2019/12/11/9
- https://github.com/rapid7/metasploit-framework/tree/master/modules/exploits/openbsd/local/dynamic_loader_chpass_privesc.rb