CVE-2026-24471

CVE-2026-24471 is a critical-severity vulnerability with a CVSS 4.0 base score of 9.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-441.

Key facts

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.

Frequently asked questions

What is CVE-2026-24471?
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.
How severe is CVE-2026-24471?
CVE-2026-24471 has a CVSS 4.0 base score of 9.3, rated critical severity.
Is CVE-2026-24471 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-24471?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-24471 have an EU (EUVD) identifier?
Yes. CVE-2026-24471 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5304.
When was CVE-2026-24471 published?
CVE-2026-24471 was published on 2026-02-02 and last updated on 2026-06-17.

References

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