CVE-2020-6809

critical

Published — · Modified —

CVSS v3

—

CVSS v2

—

VIR risk

9.5

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.

Predictions

Exploit likelihood

20%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2020-6809

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2020-6809.html

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202003-8

OS impact

OS	Version	Status	Fixed in
arch		fixed	`74.0-1`
sles		affected
debian	sid	fixed	`74.0-1`

References

https://security.archlinux.org/ASA-202003-8
https://www.suse.com/security/cve/CVE-2020-6809.html
https://security-tracker.debian.org/tracker/CVE-2020-6809

Verify integrity in audit chain (admin only). AS-IS.