Matrix Rust SDK: Sender-binding gaps in to-device and room-key attribution
### Impact The `matrix-sdk-crypto` crate before 0.16.1 is missing a check for the sender's user ID when decrypting an Olm-encrypted to-device message containing the `sender_device_keys` property. This could be exploited to spoof the sender of an encrypted to-device message, but only if the attacker colludes with (or is) the homeserver operator. ### Patches This issue is fixed in `matrix-sdk-crypto` 0.16.1. ### Workarounds There are no known workarounds for the issue. ### References This issue was fixed in https://github.com/matrix-org/matrix-rust-sdk/pull/6553. ### For more information If you have any questions or comments about this advisory, please email us at [security at matrix.org](mailto:security@matrix.org).
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-45056US | — | — | ||
matrix-sdk-crypto is a no-network-IO implementation of a state machine that handles end-to-end encryption for Matrix clients. Starting in version 0.12.0 and prior to version 0.17.0… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/matrix-org/matrix-rust-sdkPACKAGE
- https://github.com/matrix-org/matrix-rust-sdk/pull/6553WEB
- https://github.com/matrix-org/matrix-rust-sdk/releases/tag/matrix-sdk-0.16.1WEB
- https://github.com/matrix-org/matrix-rust-sdk/security/advisories/GHSA-wfq4-36m3-9g42WEB
- https://rustsec.org/advisories/RUSTSEC-2026-0159.htmlWEB
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