Vulnerability Details : CVE-2020-8833
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.
Vulnerability category: Gain privilege
Products affected by CVE-2020-8833
- cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*
- cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
- cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
- cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
- cpe:2.3:a:apport_project:apport:-:*:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2020-8833
0.06%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 26 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2020-8833
| Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
|---|---|---|---|---|---|---|
|
1.9
|
LOW | AV:L/AC:M/Au:N/C:P/I:N/A:N |
3.4
|
2.9
|
NIST | |
|
4.7
|
MEDIUM | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N |
1.0
|
3.6
|
NIST | |
|
5.6
|
MEDIUM | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N |
1.1
|
4.0
|
Canonical Ltd. |
CWE ids for CVE-2020-8833
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The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state.Assigned by:
- nvd@nist.gov (Primary)
- security@ubuntu.com (Secondary)
References for CVE-2020-8833
-
https://usn.ubuntu.com/4315-1/
USN-4315-1: Apport vulnerabilities | Ubuntu security noticesThird Party Advisory
-
https://bugs.launchpad.net/ubuntu/+source/apport/+bug/1862933
Bug #1862933 “Apport crash report & cron script TOCTTOU” : Bugs : apport package : UbuntuExploit;Third Party Advisory
-
https://usn.ubuntu.com/4315-2/
USN-4315-2: Apport vulnerabilities | Ubuntu security noticesThird Party Advisory
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