When matrix-nio receives forwarded room keys, the receiver doesn't check if it requested the key from the forwarder
When matrix-nio before 0.20 requests a room key from our devices, it correctly accepts key forwards only if they are a response to a previous request. However, it doesn't check that the device that responded matches the device the key was requested from.
This allows a malicious homeserver to insert room keys of questionable validity into the key store in some situations, potentially assisting in an impersonation attack.
For more information
If you have any questions or comments about this advisory, e-mail us at poljar@termina.org.uk.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | matrix-nio | < 0.20 | 0.20 |
References
- https://github.com/poljar/matrix-nio/security/advisories/GHSA-w4pr-4vjg-hffh
- https://nvd.nist.gov/vuln/detail/CVE-2022-39254
- https://github.com/poljar/matrix-nio/commit/b1cbf234a831daa160673defd596e6450e9c29f0
- https://github.com/poljar/matrix-nio
- https://pypi.org/project/matrix-nio
- https://github.com/advisories/GHSA-w4pr-4vjg-hffh
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N- Weakness (CWE)
CWE-287, CWE-322- Platform
- Python (PyPI)
- Package
matrix-nio- Disclosed
- 30.09.2022
- Updated
- 11.10.2026 13:18
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-842 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-w4pr-4vjg-hffh - CC BY 4.0
Vulnerability history: matrix-nio
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.