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CVE-2021-3782

Published: 30 August 2022

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.

Priority

Medium

Cvss 3 Severity Score

6.6

Score breakdown

Status

Package Release Status
wayland
Launchpad, Ubuntu, Debian
kinetic Not vulnerable
(1.21.0-1)
bionic
Released (1.16.0-1ubuntu1.1~18.04.4)
focal
Released (1.18.0-1ubuntu0.1)
jammy
Released (1.20.0-1ubuntu0.1)
trusty Ignored
(end of standard support)
upstream Needs triage

xenial
Released (1.12.0-1~ubuntu16.04.3+esm1)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
Patches:
upstream: https://gitlab.freedesktop.org/wayland/wayland/-/commit/b19488c7154b902354cb26a27f11415d7799b0b2

Severity score breakdown

Parameter Value
Base score 6.6
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