matrix-sdk-ui: Incomplete edit validation

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.9 · CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-45057: 0.23% estimated exploitation activity in the next 30 days; percentile 14.24 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact The message edit validation logic in the matrix-sdk-ui crate before 0.16.1 is missing a check: when replacing an encrypted event, the replacement event itself is not required to be encrypted. This enables a malicious homeserver administrator (or an actor with equivalent power) to impersonate or spoof messages as if they were sent by a victim user. Patches matrix-sdk-ui 0.16.1 fixes the message edit validation logic to align with the algorithm for replacement events[^1] described in the Matrix specification. Workarounds N/A References Pull request: https://github.com/matrix-org/matrix-rust-sdk/pull/6454 For more information If you have any questions or comments about this advisory, please email us at security at matrix.org. [^1]: https://spec.matrix.org/unstable/client-server-api/#validity-of-replacement-events

Published by the source

4 Jun 2026, 14:50 UTC

Last modified by the source

4 Jun 2026, 14:50 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-h97m-27fx-42rx

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# Patch Next advisory brief: CVE-2026-45057

Advisory: matrix-sdk-ui: Incomplete edit validation
IDs: CVE-2026-45057, GHSA-h97m-27fx-42rx
Record: https://patchnext.com/advisories/cve-2026-45057 (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: matrix-sdk-ui 0.16.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io matrix-sdk-ui: affected < 0.16.1; fixed in 0.16.1

## Suggested inspection (read-only)
- crates.io matrix-sdk-ui: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on matrix-sdk-ui.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-h97m-27fx-42rx (GitHub-reviewed advisory GHSA-h97m-27fx-42rx lists affected ranges: crates.io matrix-sdk-ui >=0 <0.16.1)

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