Vulnerability · Published Sep 11, 2026 · Assigned by GitHub_M

CVE-2026-45056Matrix Rust SDK: Sender-binding gaps in to-device and room-key attribution

Medium 6.9

In plain English

A medium-severity authentication bypass by spoofing in matrix-rust-sdk from matrix-org. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities).

Severity (CVSS 4.0)6.9Medium

Exploit odds (30 days)0.3%top 76.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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, the matrix-sdk-crypto crate was missing a check for the user ID when decrypting an Olm-encrypted event containing the `sender_device_keys` property. This could be exploited to forge an encrypted to-device event, but only if the attacker colludes with the homeserver operator. This issue is fixed in matrix-sdk-crypto 0.17.0. There are no known workarounds for the issue.

Affected products (as reported)

Vendor	Product	Versions
matrix-org	matrix-rust-sdk	>= 0.12.0, < 0.16.1

Weakness: CWE-290 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

References

https://github.com/matrix-org/matrix-rust-sdk/security/advisories/GHSA-wfq4-36m3-9g42 x_refsource_CONFIRM
https://github.com/matrix-org/matrix-rust-sdk/pull/6553 x_refsource_MISC
https://github.com/matrix-org/matrix-rust-sdk/releases/tag/matrix-sdk-0.16.1 x_refsource_MISC
https://rustsec.org/advisories/RUSTSEC-2026-0159.html x_refsource_MISC