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Vulnerability record · CVE-2020-8831 · published 22 April 2020

CVE-2020-8831: Canonical ubuntu linux link following vulnerability

Canonical · Ubuntu Linux

Apport creates a world writable lock file with root ownership in the world writable /var/lock/apport directory. If the apport/ directory does not exist (this is not uncommon as /var/lock is a tmpfs), it will create the directory, otherwise it will simply continue execution using the existing directory. This allows for a symlink attack if an attacker were to create a symlink at /var/lock/apport, changing apport's lock file location. This file could then be used to escalate privileges, for example. Fixed in versions 2.20.1-0ubuntu2.23, 2.20.9-0ubuntu7.14, 2.20.11-0ubuntu8.8 and 2.20.11-0ubuntu22.

5.5 CVSS 3.1 Medium EPSS 0.65% · top 50.6% CWE-379 · CWE-379CWE-59 · Link following
5.5CVSS 3.1 base score, v2 2.1
0.65%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
6References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

Apport creates a world writable lock file with root ownership in the world writable /var/lock/apport directory. If the apport/ directory does not exist (this is not uncommon as /var/lock is a tmpfs), it will create the directory, otherwise it will simply continue execution using the existing directory. This allows for a symlink attack if an attacker were to create a symlink at /var/lock/apport, changing apport's lock file location. This file could then be used to escalate privileges, for example. Fixed in versions 2.20.1-0ubuntu2.23, 2.20.9-0ubuntu7.14, 2.20.11-0ubuntu8.8 and 2.20.11-0ubuntu22.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://launchpad.net/bugs/1862348 ExploitThird Party Advisory
https://usn.ubuntu.com/4315-1/ Third Party Advisory
https://usn.ubuntu.com/4315-2/ Third Party Advisory
https://launchpad.net/bugs/1862348 ExploitThird Party Advisory
https://usn.ubuntu.com/4315-1/ Third Party Advisory
https://usn.ubuntu.com/4315-2/ Third Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2020-8831), CISA KEV, FIRST EPSS (scores of 2026-10-04). This page is refreshed as NVD updates the record.