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

High severity GitHub Reviewed Published Sep 29, 2022 in matrix-nio/matrix-nio • Updated Sep 7, 2023

Package

pip matrix-nio (pip)

Affected versions

< 0.20

Patched versions

0.20

Description

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.

References

@poljar poljar published to matrix-nio/matrix-nio Sep 29, 2022
Published by the National Vulnerability Database Sep 29, 2022
Published to the GitHub Advisory Database Sep 30, 2022
Reviewed Sep 30, 2022
Last updated Sep 7, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

EPSS score

0.050%
(21st percentile)

Weaknesses

CVE ID

CVE-2022-39254

GHSA ID

GHSA-w4pr-4vjg-hffh

Source code

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