CVE-2022-39254Network attack vector

Impersonation via unchecked forwarded room-key sender

Published Sep 29, 2022 · Updated Apr 23, 2025

Key-forward authentication failure in poljar matrix-nio before 0.20 allows remote attackers controlling a homeserver to insert room keys. The _handle_forwarded_room_key_event path validated the requested session, algorithm, and room but accepted the key without verifying the sender device identity or trust before storing it. Exploitation requires control of the homeserver and a prior room-key request, allowing injected keys to support impersonation of encrypted-room participants.

CVSS severity2.7
Low
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Key-forward authentication failure in poljar matrix-nio before 0.20 allows remote attackers controlling a homeserver to insert room keys. The _handle_forwarded_room_key_event path validated the requested session, algorithm, and room but accepted the key without verifying the sender device identity or trust before storing it. Exploitation requires control of the homeserver and a prior room-key request, allowing injected keys to support impersonation of encrypted-room participants.

The record

CVE
CVE-2022-39254
Published
Sep 29, 2022
Updated
Apr 23, 2025
Vendor
poljar
Product
matrix-nio
Classifications
CWE-287, CWE-322, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 29, 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=< 0.20

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

poljar · matrix-nioversion=< 0.20

Published CVSS scores

8.6GitHub CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
2.7GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
CWE-322Key Exchange without Entity 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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