RUSTSEC-2026-0159: Sender-binding gaps in to-device messages

What to do

1. See which version you have: cargo tree -i matrix-sdk-crypto (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p matrix-sdk-crypto. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example matrix-sdk-crypto = "0.16.1") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

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.

References

• Package: crates.io/crates/matrix-sdk-crypto
• Advisory: rustsec.org/advisories/RUSTSEC-2026-0159.html
• Web: github.com/matrix-org/matrix-rust-sdk/pull/6553

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.

Other advisories for matrix-sdk-crypto

• Vulnerability HighRUSTSEC-2022-0085 · 2022-09-29matrix-sdk Impersonation of room keys
• VulnerabilityRUSTSEC-2024-0356 · 2024-07-18`UserIdentity::is_verified` not checking verification status of own user identity while performing the check
• NoticeRUSTSEC-2024-0434 · 2024-01-07 Missing facility to signal rotation of a verified cryptographic identity
• Vulnerability MediumRUSTSEC-2025-0041 · 2025-06-11matrix-sdk-crypto vulnerable to encrypted event sender spoofing by homeserver administrator
• VulnerabilityRUSTSEC-2026-0318 · 2026-09-29Sending custom to-device messages may panics
• VulnerabilityGHSA-9ggc-845v-gcgv · 2024-05-13matrix-sdk-crypto contains a log exposure of private key of the server-side key backup

Full security history of matrix-sdk-crypto