CVE-2021-21320

Name: CVE-2021-21320
Creator: NVD / NIST
Published: 2021-03-02T03:15:13.213+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.3/10EPSS 0.92%

Last modified Jun 17, 2026

CVE-2021-21320 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. matrix-react-sdk is an npm package which is a Matrix SDK for React Javascript. In matrix-react-sdk before version 3.15.0, the user content sandbox can be abused to trick users into opening unexpected documents. EPSS estimates a 0.92% chance of exploitation in the next 30 days.

Description

matrix-react-sdk is an npm package which is a Matrix SDK for React Javascript. In matrix-react-sdk before version 3.15.0, the user content sandbox can be abused to trick users into opening unexpected documents. The content is opened with a `blob` origin that cannot access Matrix user data, so messages and secrets are not at risk. This has been fixed in version 3.15.0.

Metrics

CVSS 3.1

4.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

EPSS Probability

0.92%

55.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-345

Affected Software

Vendor	Product	Versions
Matrix-React-Sdk Project	Matrix-React-Sdk	< 3.15.0

References

https://github.com/matrix-org/matrix-react-sdk/commit/b386f0c73b95ecbb6ea7f8f79c6ff5171a8dedd1Patch, Third Party Advisory
https://github.com/matrix-org/matrix-react-sdk/pull/5657Patch, Third Party Advisory
https://github.com/matrix-org/matrix-react-sdk/security/advisories/GHSA-52mq-6jcv-j79xThird Party Advisory
https://www.npmjs.com/package/matrix-react-sdkProduct, Third Party Advisory
https://github.com/matrix-org/matrix-react-sdk/commit/b386f0c73b95ecbb6ea7f8f79c6ff5171a8dedd1Patch, Third Party Advisory
https://github.com/matrix-org/matrix-react-sdk/pull/5657Patch, Third Party Advisory
https://github.com/matrix-org/matrix-react-sdk/security/advisories/GHSA-52mq-6jcv-j79xThird Party Advisory
https://www.npmjs.com/package/matrix-react-sdkProduct, Third Party Advisory

Timeline

Published: Mar 2, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21320?

How severe is CVE-2021-21320?

CVE-2021-21320 has a CVSS score of 4.3/10 (MEDIUM severity). The EPSS model estimates a 0.92% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21320?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-21320?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST