What’s Vulnerable › Vulnerabilities

CVE-2020-6809

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-03-25 · updated 2026-06-17

Description

When a Web Extension had the all-urls permission and made a fetch request with a mode set to 'same-origin', it was possible for the Web Extension to read local files. This vulnerability affects Firefox < 74.

Affected products

• Mozilla Firefox: before 74.0 — fixed in 74.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 74.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1420296
• https://www.mozilla.org/security/advisories/mfsa2020-08/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1420296
• https://www.mozilla.org/security/advisories/mfsa2020-08/

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