PT-2021-22960 · Schildichat+5 · Schildichat Web+7
CVSS v3.1
5.9
Medium
| Vector | AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
Name of the Vulnerable Software and Affected Versions
matrix-js-sdk versions prior to 12.4.1
Element Web versions 1.8.2 and earlier
Element Desktop versions 1.8.2 and earlier
SchildiChat Web versions 1.7.32-sc1 and earlier
SchildiChat Desktop versions 1.7.32-sc1 and earlier
Cinny versions 1.2.0 and earlier
Description
A logic error in the room key sharing functionality allows a malicious Matrix homeserver present in an encrypted room to steal room encryption keys that were originally sent by affected Matrix clients participating in that room. This enables the homeserver to decrypt end-to-end encrypted messages sent by affected clients. The issue affects clients using vulnerable versions of matrix-js-sdk.
Recommendations
For matrix-js-sdk versions prior to 12.4.1, update to version 12.4.1 or later to resolve the issue.
For Element Web versions 1.8.2 and earlier, update to a version later than 1.8.2.
For Element Desktop versions 1.8.2 and earlier, update to a version later than 1.8.2.
For SchildiChat Web versions 1.7.32-sc1 and earlier, update to a version later than 1.7.32-sc1.
For SchildiChat Desktop versions 1.7.32-sc1 and earlier, update to a version later than 1.7.32-sc1.
For Cinny versions 1.2.0 and earlier, update to a version later than 1.2.0.
As a temporary workaround, consider taking vulnerable clients offline or signing them out to prevent a homeserver from stealing room keys. When signing out, set up Secure Backup or export E2E room keys to preserve access to past messages.
Fix
Authentication Bypass by Spoofing
Information Disclosure
Use of a Broken Cryptographic Algorithm
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Related Identifiers
Affected Products
Alt Linux
Cinny
Debian
Element Desktop
Element Web
Schildichat Desktop
Schildichat Web
Matrix-Js-Sdk