CVE-2022-39250 | Matrix JavaScript SDK vulnerable to key/device identifier confusion in SAS verification

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.

Published: 2022-09-29 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2022-39250 is rated Moderate Risk (54.5/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.93%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2022-39250

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.34% 0.93% +0.59%
2 2025-12-08 0.17% 0.34% +0.17%
3 2025-11-21 — 0.17% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2022-39250

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.6 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 4.0 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2022-39250

GitHub Security Advisory for CVE-2022-39250

GHSA-5w8r-8pgj-5jmf · Severity: high · Ecosystem: npm — matrix-js-sdk subject to user impersonation due to key/device identifier confusion in SAS verification

OS Trackers for CVE-2022-39250

vendor priority summary link
alpine high CVE-2022-39250: 2 source package rows (element-web, riot-web); 8 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 8, open 0. https://security.alpinelinux.org/vuln/CVE-2022-39250
debian not yet assigned CVE-2022-39250 not yet assigned priority: Debian including 1 source packages (node-matrix-js-sdk), 1 status rows across 1 suites (bullseye): open 1. https://security-tracker.debian.org/tracker/CVE-2022-39250
gentoo high CVE-2022-39250: 1 GLSA(s) (202210-35), 2 atom(s) (mail-client/thunderbird, mail-client/thunderbird-bin); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2022-39250
redhat high — https://access.redhat.com/security/cve/CVE-2022-39250
suse high CVE-2022-39250 severity important: SUSE including 11 source package names (MozillaThunderbird-102.3.1-1.1, MozillaThunderbird-102.4.0-150200.8.85.1, …), 50 product×package rows across 19 product lines (SUSE Liberty Linux 7, SUSE Liberty Linux 8, … (19 product lines)): Fixed 50. https://www.suse.com/security/cve/CVE-2022-39250/
ubuntu medium CVE-2022-39250 medium priority: Ubuntu including 2 source packages (node-matrix-js-sdk, thunderbird), 26 status rows across 13 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 7, not-affected 6, needs-triage 5, DNE 4, released 4. https://ubuntu.com/security/CVE-2022-39250

Affected software / configurations for CVE-2022-39250

Vendor Product Version Raw CPE
matrix javascript_sdk < 19.7.0 cpe:2.3:a:matrix:javascript_sdk:*:*:*:*:*:node.js:*:*

References for CVE-2022-39250

cvelogic Threat Intelligence