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TI-2021-19430 Aliases CVE-2021-43540GHSA-vj37-39rq-5f3g

WebExtensions with the correct permissions were able to create and install ServiceWorkers…

Priority LOW 31Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · High · None
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA.

Summary

WebExtensions with the correct permissions were able to create and install ServiceWorkers for third-party websites that would not have been uninstalled with the extension. This vulnerability affects Firefox < 95.

Why it matters now

EPSS 0.0089 59th percentileScored 2026-11-07
Fix Fixed Firefox (Mozilla): 95

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
MozillaFirefoxbefore 9595Patch availableCNA
  • Firefox VendorMozilla Affected before 95 Fixed in 95 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*before 95.0VulnerableMozilla
  • cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 95.0 Vulnerable ·Mozilla

Remediation

  • Fix · CNA Firefox (Mozilla) Fixed in 95

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Mozilla Firefox 95

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2021-19434 Cross-site scripting in Mozilla FirefoxPriority LOW 28
    Show all 2 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-43540
  2. 2026-10-03 Alias added: GHSA-vj37-39rq-5f3g

References

Advisory 3

  • TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
  • TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
  • TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
  • TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
  • TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
  • TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
See all 3444 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences