File upload local preview can run embedded scripts after user interaction

Exploitation

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

CVSS

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

EPSS

• CVE-2021-32622: 0.37% estimated exploitation activity in the next 30 days; percentile 31.34 (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 When uploading a file, the local file preview can lead to execution of scripts embedded in the uploaded file, but only after several user interactions to open the preview in a separate tab. This only impacts the local user while in the process of uploading. It cannot be exploited remotely or by other users. Patches This has been fixed by https://github.com/matrix-org/matrix-react-sdk/pull/5981, which is included in 3.21.0. Workarounds There are no known workarounds.

Published by the source

17 May 2021, 20:51 UTC

Last modified by the source

8 Jul 2026, 06:49 UTC

Source last checked

26 Oct 2026, 12:15 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-8796-gc9j-63rv

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-cg57-p69r-3m7p

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-8796-gc9j-63rv

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# Patch Next advisory brief: CVE-2021-32622

Advisory: File upload local preview can run embedded scripts after user interaction
IDs: CVE-2021-32622, GHSA-8796-gc9j-63rv
Record: https://patchnext.com/advisories/cve-2021-32622 (revision 3, source checked 26 Oct 2026, 12:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: matrix-react-sdk 3.21.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm matrix-react-sdk: affected < 3.21.0; fixed in 3.21.0

## Suggested inspection (read-only)
- `npm ls matrix-react-sdk --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## 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-react-sdk.
- 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://osv.dev/vulnerability/GHSA-8796-gc9j-63rv (OSV record GHSA-8796-gc9j-63rv lists affected ranges: npm matrix-react-sdk >=0 <3.21.0 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-cg57-p69r-3m7p (OSV record GHSA-cg57-p69r-3m7p lists affected ranges: npm matrix-react-sdk >=0 <3.21.0 (fixed))
- Verified: https://github.com/advisories/GHSA-8796-gc9j-63rv (GitHub-reviewed advisory GHSA-8796-gc9j-63rv lists affected ranges: npm matrix-react-sdk >=0 <3.21.0)

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