CVE-2022-39254: matrix-nio is a Python Matrix client library, designed according to sans I/O principles

Q: How do I fix CVE-2022-39254?

matrix-nio: upgrade to 0.20. Exact commands for each OS are on this page.

Q: Is CVE-2022-39254 being exploited?

CVE-2022-39254 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2022-39254 affect?

CVE-2022-39254 affects matrix-nio. Severity is high (CVSS 8.6). matrix-nio is a Python Matrix client library, designed according to sans I/O principles. Prior to version 0.20, when a users requests a room key from their devices, the software correctly remember the request. Once they receive a forwarded

Q: How urgent is CVE-2022-39254?

Priority 48/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 8.6REMOTEUPGRADE

CVE-2022-39254 is a high-severity flaw (CVSS 8.6) affecting matrix-nio. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

matrix-nio is a Python Matrix client library, designed according to sans I/O principles. Prior to version 0.20, when a users requests a room key from their devices, the software correctly remember the request. Once they receive a forwarded room key, they accept it without checking who the room key came from. This allows homeservers to try to insert room keys of questionable validity, potentially mounting an impersonation attack. Version 0.20 fixe

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 48%)
CISA exploited list	No
Weakness	CWE-287, CWE-322
Published	2022-09-29
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: matrix-nio project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-09-29 15:15 UTCPublished CVE record published
2026-06-17 04:58 UTCUpdated Record last modified

matrix-nio project matrix-nio UPGRADE

Affected: < 0.20

Fixed in: 0.20

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy matrix-nio || rpm -q matrix-nio || matrix-nio --version

2. UPGRADE to 0.20 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade matrix-nio

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade matrix-nio

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2022-39254?

matrix-nio: upgrade to 0.20. Exact commands for each OS are on this page.

Is CVE-2022-39254 being exploited?

CVE-2022-39254 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2022-39254 affect?

CVE-2022-39254 affects matrix-nio. Severity is high (CVSS 8.6). matrix-nio is a Python Matrix client library, designed according to sans I/O principles. Prior to version 0.20, when a users requests a room key from their devices, the software correctly remember the request. Once they receive a forwarded

How urgent is CVE-2022-39254?

Priority 48/100. High severity; Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

References

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