CVE-2021-3738

Publication date 9 November 2021

Last updated 24 July 2024

Ubuntu priority

Cvss 3 Severity Score

In DCE/RPC it is possible to share the handles (cookies for resource state) between multiple connections via a mechanism called 'association groups'. These handles can reference connections to our sam.ldb database. However while the database was correctly shared, the user credentials state was only pointed at, and when one connection within that association group ended, the database would be left pointing at an invalid 'struct session_info'. The most likely outcome here is a crash, but it is possible that the use-after-free could instead allow different user state to be pointed at and this might allow more privileged access.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
samba	23.04 lunar	Fixed 2:4.13.14+dfsg-0ubuntu1
	22.10 kinetic	Fixed 2:4.13.14+dfsg-0ubuntu1
	22.04 LTS jammy	Fixed 2:4.13.14+dfsg-0ubuntu1
	21.10 impish	Fixed 2:4.13.14+dfsg-0ubuntu0.21.10.1
	21.04 hirsute	Fixed 2:4.13.14+dfsg-0ubuntu0.21.04.1
	20.04 LTS focal	Fixed 2:4.13.14+dfsg-0ubuntu0.20.04.1
	18.04 LTS bionic	Ignored
	16.04 LTS xenial	Ignored change too intrusive
	14.04 LTS trusty	Ignored change too intrusive

Notes

mdeslaur

Fixing this in Ubuntu 18.04 LTS would require substantial code backports. We will not be fixing this issue in Ubuntu 18.04 LTS. In environments where this is of concern, we recommend updating to a more recent Ubuntu version.

Severity score breakdown

Parameter	Value
Base score	8.8 · High
Attack vector	Network
Attack complexity	Low
Privileges required	Low
User interaction	None
Scope	Unchanged
Confidentiality	High
Integrity impact	High
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

USN-5142-1
Samba vulnerabilities
11 November 2021