CVE-2021-3782

Publication date 30 August 2022

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

An internal reference count is held on the buffer pool, incremented every time a new buffer is created from the pool. The reference count is maintained as an int; on LP64 systems this can cause the reference count to overflow if the client creates a large number of wl_shm buffer objects, or if it can coerce the server to create a large number of external references to the buffer storage. With the reference count overflowing, a use-after-free can be constructed on the wl_shm_pool tracking structure, where values may be incremented or decremented; it may also be possible to construct a limited oracle to leak 4 bytes of server-side memory to the attacking client at a time.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
wayland	22.10 kinetic	Not affected
	22.04 LTS jammy	Fixed 1.20.0-1ubuntu0.1
	20.04 LTS focal	Fixed 1.18.0-1ubuntu0.1
	18.04 LTS bionic	Fixed 1.16.0-1ubuntu1.1~18.04.4
	16.04 LTS xenial	Fixed 1.12.0-1~ubuntu16.04.3+esm1
	14.04 LTS trusty	Ignored end of standard support

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Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
wayland	Upstream: b19488c

Severity score breakdown

Parameter	Value
Base score	6.6 · Medium
Attack vector	Local
Attack complexity	Low
Privileges required	Low
User interaction	None
Scope	Unchanged
Confidentiality	Low
Integrity impact	Low
Availability impact	High
Vector	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H