GHSA-w4pr-4vjg-hffh — high GitHub Advisory (CVE-2022-39254) in pip/matrix-nio

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

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Basic information

Type: reviewed
Severity: high
Advisory on GitHub: Open advisory ↗
Repository advisory: Open repository advisory ↗
Source code: Browse source ↗
Published (advisory): 2022-09-30 22:56:17 UTC
Updated: 2023-09-07 20:46:29 UTC
GitHub reviewed: 2022-09-30 22:56:17 UTC
NVD published: 2022-09-29

Score	Percentile
0.24%	47.65%

CVSS Scores

Base score	Version	Severity	Vector
8.6	3.1	—	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.

Identifiers

Type	Value
GHSA	GHSA-w4pr-4vjg-hffh ↗
CVE	CVE-2022-39254 ↗

CWEs

CWE id	Name
CWE-287	Improper Authentication
CWE-322	Key Exchange without Entity Authentication

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
pip	matrix-nio	< 0.20	0.20	—

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