What is CVE-2021-29979?

CVE-2021-29979 is a medium-severity vulnerability in Mozilla Hubs Cloud, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-08-02.

How severe is CVE-2021-29979?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Mozilla Hubs Cloud

CVE-2021-29979

Hubs Cloud allows users to download shared content, specifically HTML and JS, which could allow javascript execution in the Hub Cloud instance’s primary hosting domain.*. This vulnerability affects Hubs Cloud < mozillareality/reticulum/1.0.1/20210618012634.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-08-02 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.007 (50.0th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Mozilla Hubs Cloud — versions unspecified
Mozilla Hubs Cloud

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

www.mozilla.org/security/advisories/mfsa2021-32/ (Vendor Advisory)
bugzilla.mozilla.org/show_bug.cgi (Permissions Required)

Frequently asked questions

What is CVE-2021-29979?: CVE-2021-29979 is a medium-severity vulnerability in Mozilla Hubs Cloud, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-08-02.
How severe is CVE-2021-29979?: Medium severity. CVSS v3 base score is 6.1 out of 10.