When matrix-nio receives forwarded room keys, the receiver doesn't check if it requested the key from the forwarder
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-287.
Summary
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 fixes the issue.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| poljar | matrix-nio | before 0.20 | 0.20 | Patch available | CNA |
| — | matrix-nio (PyPI) | before 0.20 | 0.20 | Patch available | GHSA-w4pr-4vjg-hffh |
- matrix-nio Vendorpoljar Affected before 0.20 Fixed in 0.20 Patch available CNA
- matrix-nio (PyPI) Vendor— Affected before 0.20 Fixed in 0.20 Patch available GHSA-w4pr-4vjg-hffh
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:matrix-nio_project:matrix-nio:*:*:*:*:*:*:*:* | before 0.20 | Vulnerable | Matrix-nio Project |
- cpe:2.3:a:matrix-nio_project:matrix-nio:*:*:*:*:*:*:*:* Versions before 0.20 Vulnerable ·Matrix-nio Project
Remediation
- Fix · CNA matrix-nio (poljar) Fixed in 0.20
- Fix · GHSA-w4pr-4vjg-hffh matrix-nio (PyPI) Fixed in 0.20 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2022-39254
- 2026-10-03 Alias added: GHSA-w4pr-4vjg-hffh
- 2026-10-06 EPSS moved to the 50th–90th percentile
References
Sources
- CVE-2022-39254 · CVE Program
- CVE-2022-39254 · NVD
- FIRST EPSS
- GHSA-w4pr-4vjg-hffh · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences