CVE-2018-16841 Use after free in samba

What is CVE-2018-16841?

CVE-2018-16841 is a medium-severity use after free vulnerability in Canonical Ubuntu Linux, published on 28 Nov 2018. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

Samba from version 4.3.0 and before versions 4.7.12, 4.8.7 and 4.9.3 are vulnerable to a denial of service. When configured to accept smart-card authentication, Samba's KDC will call talloc_free() twice on the same memory if the principal in a validly signed certificate does not match the principal in the AS-REQ. This is only possible after authentication with a trusted certificate. talloc is robust against further corruption from a double-free with talloc_free() and directly calls abort(), terminating the KDC process.

Weakness: CWE-415, CWE-416

Which versions are affected by CVE-2018-16841?

It affects 3 products.

Products include Canonical Ubuntu Linux, Debian Debian Linux, Samba Samba.

How do I fix CVE-2018-16841?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2018-16841 being exploited?

There is no known exploitation of CVE-2018-16841 in the wild and no public exploit code.

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 ALPINE-CVE-2018-16841, DEBIAN-CVE-2018-16841, ECHO-3243-5f1a-98b7, GHSA-q3v8-mj9m-2wq4, UBUNTU-CVE-2018-16841.