CVE-2018-15686 systemd: reexec state injection: fgets() on overlong lines leads to line splitting

What is CVE-2018-15686?

CVE-2018-15686 is a high-severity unsafe deserialization vulnerability in Canonical Ubuntu Linux, published on 26 Oct 2018. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A vulnerability in unit_deserialize of systemd allows an attacker to supply arbitrary state across systemd re-execution via NotifyAccess. This can be used to improperly influence systemd execution and possibly lead to root privilege escalation. Affected releases are systemd versions up to and including 239.

Weakness: CWE-502

Which versions are affected by CVE-2018-15686?

It affects 4 products.

Products include Canonical Ubuntu Linux, Debian Debian Linux, Oracle Communications Cloud Native Core Network Function Cloud Native Environment, Systemd Project Systemd.

How do I fix CVE-2018-15686?

Apply the vendor's patch.

Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.

Is CVE-2018-15686 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2018-15686 exists.

Public exploit code: 1 Exploit-DB entry and 1 proofs of concept on GitHub.

Other vulnerabilities in Canonical Ubuntu Linux

• CVE-2020-11651 SaltStack Salt Authentication Bypass Exploited Critical 9.8
• CVE-2020-7247 OpenSMTPD Remote Code Execution Exploited Critical 9.8
• CVE-2019-16928 Exim Out-of-bounds Write Exploited Critical 9.8
• CVE-2018-6789 Exim Buffer Overflow Exploited Critical 9.8
• CVE-2015-2590 Oracle Java SE and Java SE Embedded Remote Code Execution Exploited Critical 9.8

All Canonical Ubuntu Linux vulnerabilities

Sources

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

Also known as DEBIAN-CVE-2018-15686, GHSA-86rx-vp92-xvgg, UBUNTU-CVE-2018-15686.