Today we are issuing security releases of matrix-js-sdk and matrix-react-sdk to patch a couple of High severity vulnerabilities (reserved as CVE-2022-36059 for the matrix-js-sdk and CVE-2022-36060 for the matrix-react-sdk).
Affected clients include those which depend on the affected libraries, such as Element Web/Desktop and Cinny. Releases of the affected clients will follow shortly. We advise users of those clients to upgrade at their earliest convenience.
The vulnerabilities give an adversary who you share a room with the ability to carry out a denial-of-service attack against the affected clients, making it not show all of a user's rooms or spaces and/or causing minor temporary corruption.
The full vulnerability details will be disclosed at a later date, to give people time to upgrade and us to perform a more thorough audit of the codebase.
Note that while the vulnerability was to our knowledge never exploited maliciously, some unintentional public testing has left some people affected by the bug. We made a best effort to sanitize this to stop the breakage. If you are affected, you may still need to clear the cache and reload your Matrix client for it to take effect.
We thank Val Lorentz who discovered and reported the vulnerability over the weekend.