CVE-2020-13776

Published: 3 June 2020

systemd through v245 mishandles numerical usernames such as ones composed of decimal digits or 0x followed by hex digits, as demonstrated by use of root privileges when privileges of the 0x0 user account were intended. NOTE: this issue exists because of an incomplete fix for CVE-2017-1000082.

Notes

The administrator would have to create a systemd service unit
with a numerical username or a username starting with 0x as a
User= value, and that particular userid would need to exist on
the system. Setting priority to low due to this unlikely
scenario.

Fixing this requires an extensive backport that refactors
integer parsing in systemd and the risk of regressions stemming
from the behavioural change outweighs the severity of this
issue. We will not be fixing this issue in stable Ubuntu
releases.

Mitigation

mdeslaur> Do not create systemd service units with a User= value set to
mdeslaur> a numerical username or a username that starts with 0x

Priority

Low

CVSS 3 base score: 6.7

Status

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-13776
• NVD
• Launchpad
• Debian

Bugs

• https://github.com/systemd/systemd/issues/15985