CVE-2018-6553: AppArmor cupsd Sandbox Bypass Due to Use of Hard Links

Severity: high (CVSS 8.8 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2018-08-10 · updated 2026-06-17

Description

The CUPS AppArmor profile incorrectly confined the dnssd backend due to use of hard links. A local attacker could possibly use this issue to escape confinement. This flaw affects versions prior to 2.2.7-1ubuntu2.1 in Ubuntu 18.04 LTS, prior to 2.2.4-7ubuntu3.1 in Ubuntu 17.10, prior to 2.1.3-4ubuntu0.5 in Ubuntu 16.04 LTS, and prior to 1.7.2-0ubuntu1.10 in Ubuntu 14.04 LTS.

Affected products

Canonical Ubuntu Linux: 14.04, 16.04, 17.10, 18.04
cups: all versions
Debian Linux: 8.0, 9.0

References

https://lists.debian.org/debian-lts-announce/2018/07/msg00014.html
https://security.gentoo.org/glsa/201908-08
https://usn.ubuntu.com/usn/usn-3713-1
https://www.debian.org/security/2018/dsa-4243
https://lists.debian.org/debian-lts-announce/2018/07/msg00014.html
https://security.gentoo.org/glsa/201908-08
https://usn.ubuntu.com/usn/usn-3713-1
https://www.debian.org/security/2018/dsa-4243

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