CVE-2022-39255Network attack vector

Trusted-sender impersonation via Megolm to-device messages

Published Sep 28, 2022 · Updated Apr 23, 2025

Protocol confusion in Matrix.org iOS SDK before 0.23.19 allows remote attackers to impersonate trusted senders through a malicious homeserver. The to-device event handling path accepts Megolm-encrypted messages where Olm is required and attributes them to the claimed Megolm sender. Exploitation requires cooperation from a malicious homeserver and can inject forged messages or a malicious key-backup secret without a trust warning.

CVSS severity7.5
High
EPSS probability0.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Protocol confusion in Matrix.org iOS SDK before 0.23.19 allows remote attackers to impersonate trusted senders through a malicious homeserver. The to-device event handling path accepts Megolm-encrypted messages where Olm is required and attributes them to the claimed Megolm sender. Exploitation requires cooperation from a malicious homeserver and can inject forged messages or a malicious key-backup secret without a trust warning.

The record

CVE
CVE-2022-39255
Published
Sep 28, 2022
Updated
Apr 23, 2025
Vendor
Matrix.org
Product
Matrix.org iOS SDK
Classifications
CWE-322, CWE-287, T1557
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Sep 28, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.23.19

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Matrix.org · Matrix.org iOS SDKversion=< 0.23.19

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-322Key Exchange without Entity Authentication
CWE-287Improper Authentication
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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