Medium severity · published Sep 13, 2021
CVE-2021-40823
A logic error in the room key sharing functionality of matrix-js-sdk (aka Matrix Javascript SDK) before 12.4.1 allows a malicious Matrix homeserver present in an encrypted room to…
5.9
CVSS
0.7%
EPSS
No
On KEV
Description
A logic error in the room key sharing functionality of matrix-js-sdk (aka Matrix Javascript SDK) before 12.4.1 allows a malicious Matrix homeserver present in an encrypted room to steal room encryption keys (via crafted Matrix protocol messages) that were originally sent by affected Matrix clients participating in that room. This allows the homeserver to decrypt end-to-end encrypted messages sent by affected clients.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 52% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
JS
Javascript Sdk · Matrix
before 12.4.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-40823
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-40823
Third Party Advisory
https://github.com/matrix-org/matrix-js-sdk/releases/tag/v12.4.1
Vendor Advisory
https://matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing
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