How severe is CVE-2021-21320?

CVE-2021-21320 has a CVSS 3.x base score of 2.6, rated low severity. It is exploitable over network with high attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-21320 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21320?

CVE-2021-21320 affects Matrix-react-sdk Project Matrix-react-sdk. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21320?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-21320 published?

CVE-2021-21320 was published on 2021-03-02 and last updated on 2026-06-17.

CVE-2021-21320

CVE-2021-21320 is a low-severity vulnerability in Matrix-react-sdk Project Matrix-react-sdk with a CVSS 3.x base score of 2.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-345.

Key facts

Severity: Low (CVSS 3.x base score 2.6)
CVSS v2: 4.3
EPSS exploit prediction: 1% (56th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-345
Affected product: Matrix-react-sdk Project Matrix-react-sdk
Published: 2021-03-02
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-21320?: 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.
How severe is CVE-2021-21320?: CVE-2021-21320 has a CVSS 3.x base score of 2.6, rated low severity. It is exploitable over network with high attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-21320 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21320?: CVE-2021-21320 affects Matrix-react-sdk Project Matrix-react-sdk. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21320?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-21320 published?: CVE-2021-21320 was published on 2021-03-02 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:matrix-react-sdk_project:matrix-react-sdk:*:*:*:*:*:node.js:*:*

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