# CVE-2026-45057

## Summary

- **CVE ID:** CVE-2026-45057
- **Severity:** MEDIUM
- **CVSS Score:** 4.9 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N)
- **CWE:** CWE-345
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 14, 2026

## Description

matrix-sdk-ui provides GUI-centric utilities on top of matrix-rust-sdk. The message edit validation logic in the  `matrix-sdk-ui` crate prior to 0.17.0 is missing a check: when replacing an encrypted event, the replacement event itself is not required to be encrypted. This enables a malicious homeserver administrators (or actors with equivalent power) to impersonate or spoof messages as if they were sent by a victim user. `matrix-sdk-ui` 0.17.0 fixes the message edit validation logic to align with the algorithm for replacement events[^1] described in the Matrix specification. No known workarounds are available.

## Affected Products

- matrix-org — matrix-sdk-ui (< 0.16.1)

## References

- [CNA](https://github.com/matrix-org/matrix-rust-sdk/security/advisories/GHSA-h97m-27fx-42rx)
- [CNA](https://github.com/matrix-org/matrix-rust-sdk/pull/6454)
- [CNA](https://github.com/matrix-org/matrix-rust-sdk/releases/tag/matrix-sdk-0.16.1)
- [CNA](https://rustsec.org/advisories/RUSTSEC-2026-0158.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.15%
- **EPSS Percentile:** 5.0

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