# CVE-2026-45056

## Summary

- **CVE ID:** CVE-2026-45056
- **Severity:** MEDIUM
- **CVSS Score:** 6.9 (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)
- **CWE:** CWE-290
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 14, 2026

## 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

- matrix-org — matrix-rust-sdk (>= 0.12.0, < 0.16.1)

## References

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

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.23%
- **EPSS Percentile:** 14.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._