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CVE-2022-39250

Published: 29 September 2022

Matrix JavaScript SDK is the Matrix Client-Server software development kit (SDK) for JavaScript. Prior to version 19.7.0, an attacker cooperating with a malicious homeserver could interfere with the verification flow between two users, injecting its own cross-signing user identity in place of one of the users’ identities. This would lead to the other device trusting/verifying the user identity under the control of the homeserver instead of the intended one. The vulnerability is a bug in the matrix-js-sdk, caused by checking and signing user identities and devices in two separate steps, and inadequately fixing the keys to be signed between those steps. Even though the attack is partly made possible due to the design decision of treating cross-signing user identities as Matrix devices on the server side (with their device ID set to the public part of the user identity key), no other examined implementations were vulnerable. Starting with version 19.7.0, the matrix-js-sdk has been modified to double check that the key signed is the one that was verified instead of just referencing the key by ID. An additional check has been made to report an error when one of the device ID matches a cross-signing key. As this attack requires coordination between a malicious homeserver and an attacker, those who trust their homeservers do not need a particular workaround.

Priority

Medium

Cvss 3 Severity Score

7.5

Score breakdown

Status

Package Release Status
node-matrix-js-sdk
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Needs triage

jammy Needs triage

kinetic Ignored
(end of life, was needs-triage)
lunar Ignored
(end of life, was needs-triage)
mantic Needs triage

noble Needs triage

trusty Ignored
(end of standard support)
upstream Needs triage

xenial Ignored
(end of standard support)
thunderbird
Launchpad, Ubuntu, Debian
bionic
Released (1:102.4.2+build2-0ubuntu0.18.04.1)
focal
Released (1:102.4.2+build2-0ubuntu0.20.04.1)
jammy
Released (1:102.4.2+build2-0ubuntu0.22.04.1)
kinetic
Released (1:102.4.2+build2-0ubuntu0.22.10.1)
lunar Not vulnerable
(1:102.6.0+build1-0ubuntu1)
mantic Not vulnerable
(1:102.6.0+build1-0ubuntu1)
noble Not vulnerable
(1:102.6.0+build1-0ubuntu1)
trusty Does not exist

upstream Needs triage

xenial Ignored
(end of standard support)

Severity score breakdown

Parameter Value
Base score 7.5
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact High
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N