CVE-2026-24471 Improper Validation in Conduit-derived homeservers resulting in Unintended Proxy or Intermediary ('Confused Deputy')
A malicious remote server can trick a Matrix homeserver into signing arbitrary events, enabling event forgery and potential compromise.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-24471?
CVE-2026-24471 is a critical vulnerability in continuwuity, published on 2 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
continuwuity is a Matrix homeserver written in Rust. This vulnerability allows an attacker with a malicious remote server to cause the local server to sign an arbitrary event upon user interaction. Upon a user account leaving a room (rejecting an invite), joining a room or knocking on a room, the victim server may ask a remote server for assistance. If the victim asks the attacker server for assistance the attacker is able to provide an arbitrary event, which the victim will sign and return to the attacker. For the /leave endpoint, this works for any event with a supported room version, where the origin and origin_server_ts is set by the victim. For the /join endpoint, an additionally victim-set content field in the format of a join membership is needed. For the /knock endpoint, an additional victim-set content field in the format of a knock membership and a room version not between 1 and 6 is needed. This was exploited as a part of a larger chain against the continuwuity.org homeserver. This vulnerability affects all Conduit-derived servers. This vulnerability is fixed in Continuwuity 0.5.1, Conduit 0.10.11, Grapevine 0aae932b, and Tuwunel 1.4.9.
Weakness: CWE-441
Which versions are affected by CVE-2026-24471?
How do I fix CVE-2026-24471?
No fix has been published for CVE-2026-24471 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-24471 being exploited?
There is no known exploitation of CVE-2026-24471 in the wild and no public exploit code.
Sources
Also known as GHSA-m5p2-vccg-8c9v.