Skip to content

When receiving forwarded room keys, we don't check that the forwarder device matches the device we requested from

Low
poljar published GHSA-vp68-2wrm-69qm Sep 29, 2022

Package

cargo matrix-sdk-crypto (Rust)

Affected versions

< 0.5

Patched versions

0.6

Description

Impact

When matrix-rust-sdk before 0.6 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. Note that even if key injection succeeds in this way, all forwarded keys have the imported flag set, which is used as an indicator that such keys have lesser authentication properties (and should be marked as such in clients, e.g. with a grey shield besides the message).

For more information

If you have any questions or comments about this advisory, e-mail us at security@matrix.org.

Severity

Low

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
High
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
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:H/UI:N/S:U/C:N/I:L/A:N

CVE ID

CVE-2022-39252

Weaknesses

No CWEs