CVE-2020-26967

critical

Published — · Modified —

CVSS v3

—

CVSS v2

—

VIR risk

9.5

Description

When listening for page changes with a Mutation Observer, a malicious web page could confuse Firefox Screenshots into interacting with elements other than those that it injected into the page. This would lead to internal errors and unexpected behavior in the Screenshots code. This vulnerability affects Firefox < 83.

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-2020-26967

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2020-26967.html

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202011-12

OS impact

OS	Version	Status	Fixed in
arch		fixed	`83.0-1`
sles		affected
debian	sid	fixed	`83.0-1`

References

https://security.archlinux.org/ASA-202011-12
https://www.suse.com/security/cve/CVE-2020-26967.html
https://security-tracker.debian.org/tracker/CVE-2020-26967

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