UNIX symbolic link following in Net-snmp - CVE-2020-15861
Published: August 17, 2020
Vulnerability identifier: #VU45744
CSH Severity: Low
CVSS v4: 8.5 [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]
CVE-ID: CVE-2020-15861
CWE-ID: CWE-61
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a symlink following issue in snmpd. A local user can bypass implemented security mechanism via *snmp-mibs-downloader package* and execute arbitrary commands on the system as root.
Affected software
Net-snmp
Gentoo Linux
Ubuntu
net-snmp (Debian package)
snmpd (Ubuntu package)
libsnmp15 (Ubuntu package)
libsnmp-perl (Ubuntu package)
libsnmp-base (Ubuntu package)
libsnmp30 (Ubuntu package)
libsnmp35 (Ubuntu package)
Enterprise SONiC
Gentoo Linux
Ubuntu
net-snmp (Debian package)
snmpd (Ubuntu package)
libsnmp15 (Ubuntu package)
libsnmp-perl (Ubuntu package)
libsnmp-base (Ubuntu package)
libsnmp30 (Ubuntu package)
libsnmp35 (Ubuntu package)
Enterprise SONiC
How to mitigate CVE-2020-15861
Install updates from vendor's website.
Net-snmp - update to 5.9
net-snmp (Debian package) - update to 5.7.3+dfsg-5+deb10u1
Enterprise SONiC - update to 4.1.4
snmpd (Ubuntu package) - addressed in versions 5.4.3~dfsg-2.4ubuntu1.5, 5.7.2~dfsg-8.1ubuntu3.3+esm1, 5.7.2~dfsg-8.1ubuntu3.3+esm2, 5.7.3+dfsg-1.8ubuntu3.5, 5.7.3+dfsg-1.8ubuntu3.6, 5.7.3+dfsg-1ubuntu4.5, 5.7.3+dfsg-1ubuntu4.6, 5.8+dfsg-2ubuntu2.3
libsnmp15 (Ubuntu package) - update to 5.4.3~dfsg-2.4ubuntu1.5
libsnmp-perl (Ubuntu package) - addressed in versions 5.4.3~dfsg-2.4ubuntu1.5, 5.7.2~dfsg-8.1ubuntu3.3+esm1, 5.7.2~dfsg-8.1ubuntu3.3+esm2, 5.7.3+dfsg-1.8ubuntu3.5, 5.7.3+dfsg-1.8ubuntu3.6, 5.7.3+dfsg-1ubuntu4.5, 5.7.3+dfsg-1ubuntu4.6, 5.8+dfsg-2ubuntu2.3
libsnmp-base (Ubuntu package) - addressed in versions 5.4.3~dfsg-2.4ubuntu1.5, 5.7.2~dfsg-8.1ubuntu3.3+esm1, 5.7.2~dfsg-8.1ubuntu3.3+esm2, 5.7.3+dfsg-1.8ubuntu3.5, 5.7.3+dfsg-1.8ubuntu3.6, 5.7.3+dfsg-1ubuntu4.5, 5.7.3+dfsg-1ubuntu4.6, 5.8+dfsg-2ubuntu2.3
libsnmp30 (Ubuntu package) - addressed in versions 5.7.2~dfsg-8.1ubuntu3.3+esm1, 5.7.2~dfsg-8.1ubuntu3.3+esm2, 5.7.3+dfsg-1.8ubuntu3.5, 5.7.3+dfsg-1.8ubuntu3.6, 5.7.3+dfsg-1ubuntu4.5, 5.7.3+dfsg-1ubuntu4.6
libsnmp35 (Ubuntu package) - update to 5.8+dfsg-2ubuntu2.3
net-snmp (Debian package) - update to 5.7.3+dfsg-5+deb10u1
Enterprise SONiC - update to 4.1.4
snmpd (Ubuntu package) - addressed in versions 5.4.3~dfsg-2.4ubuntu1.5, 5.7.2~dfsg-8.1ubuntu3.3+esm1, 5.7.2~dfsg-8.1ubuntu3.3+esm2, 5.7.3+dfsg-1.8ubuntu3.5, 5.7.3+dfsg-1.8ubuntu3.6, 5.7.3+dfsg-1ubuntu4.5, 5.7.3+dfsg-1ubuntu4.6, 5.8+dfsg-2ubuntu2.3
libsnmp15 (Ubuntu package) - update to 5.4.3~dfsg-2.4ubuntu1.5
libsnmp-perl (Ubuntu package) - addressed in versions 5.4.3~dfsg-2.4ubuntu1.5, 5.7.2~dfsg-8.1ubuntu3.3+esm1, 5.7.2~dfsg-8.1ubuntu3.3+esm2, 5.7.3+dfsg-1.8ubuntu3.5, 5.7.3+dfsg-1.8ubuntu3.6, 5.7.3+dfsg-1ubuntu4.5, 5.7.3+dfsg-1ubuntu4.6, 5.8+dfsg-2ubuntu2.3
libsnmp-base (Ubuntu package) - addressed in versions 5.4.3~dfsg-2.4ubuntu1.5, 5.7.2~dfsg-8.1ubuntu3.3+esm1, 5.7.2~dfsg-8.1ubuntu3.3+esm2, 5.7.3+dfsg-1.8ubuntu3.5, 5.7.3+dfsg-1.8ubuntu3.6, 5.7.3+dfsg-1ubuntu4.5, 5.7.3+dfsg-1ubuntu4.6, 5.8+dfsg-2ubuntu2.3
libsnmp30 (Ubuntu package) - addressed in versions 5.7.2~dfsg-8.1ubuntu3.3+esm1, 5.7.2~dfsg-8.1ubuntu3.3+esm2, 5.7.3+dfsg-1.8ubuntu3.5, 5.7.3+dfsg-1.8ubuntu3.6, 5.7.3+dfsg-1ubuntu4.5, 5.7.3+dfsg-1ubuntu4.6
libsnmp35 (Ubuntu package) - update to 5.8+dfsg-2ubuntu2.3