matrix-sdk-ui: Incomplete edit validation

### Impact The message edit validation logic in the `matrix-sdk-ui` crate before 0.16.1 is missing a check: when replacing an encrypted event, the replacement event itself is not required to be encrypted. This enables a malicious homeserver administrator (or an actor with equivalent power) to impersonate or spoof messages as if they were sent by a victim user. ### Patches `matrix-sdk-ui` 0.16.1 fixes the message edit validation logic to align with the algorithm for replacement events[^1] described in the Matrix specification. ### Workarounds N/A ### References * Pull request: https://github.com/matrix-org/matrix-rust-sdk/pull/6454 ### For more information If you have any questions or comments about this advisory, please email us at [security at matrix.org](mailto:[email protected]). [^1]: https://spec.matrix.org/unstable/client-server-api/#validity-of-replacement-events

Source published

4 Jun 2026 14:50:47 UTC

Source modified

4 Jun 2026 15:00:08 UTC

Observed here

24 Oct 2026 13:19:54 UTC

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

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