CVE-2020-8833 Apport race condition in crash report permissions

What is CVE-2020-8833?

CVE-2020-8833 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 22 Apr 2020. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Time-of-check Time-of-use Race Condition vulnerability on crash report ownership change in Apport allows for a possible privilege escalation opportunity. If fs.protected_symlinks is disabled, this can be exploited between the os.open and os.chown calls when the Apport cron script clears out crash files of size 0. A symlink with the same name as the deleted file can then be created upon which chown will be called, changing the file owner to root. Fixed in versions 2.20.1-0ubuntu2.23, 2.20.9-0ubuntu7.14, 2.20.11-0ubuntu8.8 and 2.20.11-0ubuntu22.

Weakness: CWE-367

Which versions are affected by CVE-2020-8833?

It affects 2 products.

Products include Apport Project Apport, Canonical Ubuntu Linux.

How do I fix CVE-2020-8833?

Apply the vendor's patch.

Is CVE-2020-8833 being exploited?

There is no known exploitation of CVE-2020-8833 in the wild and no public exploit code.

Other vulnerabilities in Canonical Ubuntu Linux

• CVE-2022-28657 Denial of service in Apport High 7.8
• CVE-2018-6552 Apport treats the container PID as the global PID when /proc/<global_pid>/ is missing High 7.8
• CVE-2017-14177 Privilege escalation in Apport High 7.8
• CVE-2017-14179 Privilege escalation in Apport High 7.8
• CVE-2017-14180 Privilege escalation in Apport High 7.8

All Canonical Ubuntu Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-w9g5-3qgc-xmgx, UBUNTU-CVE-2020-8833.