CVE-2022-39254

When matrix-nio receives forwarded room keys, the receiver doesn't check if it requested the key from the forwarder

Published Sep 29, 2022 CVSS 3.1 · 8.6 High EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2022-6957 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.
Github GHSA Github GHSA GHSA-w4pr-4vjg-hffh When matrix-nio receives forwarded room keys, the receiver doesn't check if it requested the key from the forwarder
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Apr 23, 2025, 4:53 PM
Reserved
Sep 2, 2022, 12:00 AM
Status
Modified
Published
Sep 29, 2022, 3:15 PM
Modified
Jun 17, 2026, 4:58 AM