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MEDIUM severity

File upload local preview can run embedded scripts after user interactionGHSA-8796-gc9j-63rv

MEDIUM

GHSA-8796-gc9j-63rv is a medium-severity (CVSS 4.2) CWE-74 vulnerability in matrix-react-sdk. A fix is available for matrix-react-sdk — see the affected versions and patch details below.

Also known asCVE-2021-32622GHSA-cg57-p69r-3m7p
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs31th percentile — riskier than 31% of all scored CVEsHighest risk
0.00%0.29%0.58%0.87%0.2%0.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

3other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
matrix-react-sdknpm
10Kdownloads / week

Description

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmmatrix-react-sdkall versions3.21.0npm install matrix-react-sdk@3.21.0

Affected Products

1 product · 1 configurations
Application
matrix-react-sdkmatrix-react-sdk_project
< 3.21.0
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for matrix-react-sdk, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update matrix-react-sdk to 3.21.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8796-gc9j-63rv is resolved across your whole dependency graph.

  3. Workarounds

    Treat uploaded files as untrusted until proven otherwise: validate the actual content type rather than the supplied extension, store uploads outside the web root on a volume mounted without execute permission, and rename them to server-generated identifiers so an attacker cannot choose the path a request will later resolve.

Frequently Asked Questions

### 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.
O3 Security · Impact-Aware SCA

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