{"action":"Upgrade firefox-esr to 91.5.0esr-1 or later.","affected":[{"fixed":"91.5.0esr-1","introduced":"0"}],"component":"firefox-esr","cve_ids":[],"ecosystem":"Debian","ecosystem_qualifier":"Debian:12","exploited":false,"fixed_versions":["91.5.0esr-1"],"id":"tcs_01M5NG04CTYA1Q4B40A3D15CTG","modified_at":"2026-10-23T18:03:38.989439710Z","published_at":"2022-12-22T20:15:12.250Z","references":["https://osv.dev/vulnerability/DEBIAN-CVE-2021-4140","https://security-tracker.debian.org/tracker/CVE-2021-4140"],"severity":{"label":"critical","score":10},"sources":[{"source":"osv","source_id":"DEBIAN-CVE-2021-4140","url":"https://osv.dev/vulnerability/DEBIAN-CVE-2021-4140"}],"summary":"It was possible to construct specific XSLT markup that would be able to bypass an iframe sandbox. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5."}