Matrix Javascript SDK is the Matrix Client-Server SDK for JavaScript. Prior to version 19.7.0, an attacker cooperating with a malicious homeserver can construct messages appearing to have come from another person. Such messages will be marked with a grey shield on some platforms, but this may be missing in others. This attack is possible due to the matrix-js-sdk implementing a too permissive key forwarding strategy on the receiving end. Starting with version 19.7.0, the default policy for accepting key forwards has been made more strict in the matrix-js-sdk. matrix-js-sdk will now only accept forwarded keys in response to previously issued requests and only from own, verified devices. The SDK now sets a `trusted` flag on the decrypted message upon decryption, based on whether the key used to decrypt the message was received from a trusted source. Clients need to ensure that messages decrypted with a key with `trusted = false` are decorated appropriately, for example, by showing a warning for such messages. This attack requires coordination between a malicious homeserver and an attacker, and those who trust your homeservers do not need a workaround.
History

No history.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2022-09-28T00:00:00

Updated: 2024-08-03T12:00:43.417Z

Reserved: 2022-09-02T00:00:00

Link: CVE-2022-39249

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2022-09-28T20:15:16.127

Modified: 2022-12-08T03:13:22.717

Link: CVE-2022-39249

cve-icon Redhat

Severity : Important

Publid Date: 2022-09-28T00:00:00Z

Links: CVE-2022-39249 - Bugzilla