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CVE-2026-45057

4.9 · MEDIUM

matrix-sdk-ui provides GUI-centric utilities on top of matrix-rust-sdk.

Published Sep 11, 2026CWE-345EPSS 0.23%

Overview

CVE-2026-45057 is a medium-severity vulnerability. It was published on September 11, 2026 and has a CVSS 3.1 base score of 4.9 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.9, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Frequently asked questions

What is CVE-2026-45057?

CVE-2026-45057 is a medium-severity vulnerability. It was published on September 11, 2026 and has a CVSS 3.1 base score of 4.9 (MEDIUM).

How severe is CVE-2026-45057?

This vulnerability has a CVSS 3.1 base score of 4.9, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-45057?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-45057?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-45057 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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