CVE-2021-3640 Use after free in kernel

What is CVE-2021-3640?

CVE-2021-3640 is a high-severity use after free vulnerability in Canonical Ubuntu Linux, published on 3 Mar 2022. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A flaw use-after-free in function sco_sock_sendmsg() of the Linux kernel HCI subsystem was found in the way user calls ioct UFFDIO_REGISTER or other way triggers race condition of the call sco_conn_del() together with the call sco_sock_sendmsg() with the expected controllable faulting memory page. A privileged local user could use this flaw to crash the system or escalate their privileges on the system.

Weakness: CWE-416, CWE-362

Which versions are affected by CVE-2021-3640?

It affects 12 products.

Products include Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Linux kernel, Netapp H300e Firmware, Netapp H300s Firmware and 6 more.

How do I fix CVE-2021-3640?

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-2021-3640 being exploited?

There is no known exploitation of CVE-2021-3640 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 DEBIAN-CVE-2021-3640, GHSA-c8w8-4f3f-5v3j, OESA-2021-1336, UBUNTU-CVE-2021-3640.