{"schemaVersion":3,"id":"CVE-2021-23961","aliases":["UBUNTU-CVE-2021-23961","DEBIAN-CVE-2021-23961"],"status":"published","duplicateOf":null,"title":null,"description":"Further techniques that built on the slipstream research combined with a malicious webpage could have exposed both an internal network's hosts as well as services running on the user's local machine. This vulnerability affects Firefox < 85.","dates":{"published":"2021-02-26T02:02:52.000Z","modified":"2024-08-03T19:14:09.837Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":7.4,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"NVD","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"OSV · Ubuntu","score":7.4,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N","exploitability":7.2,"impact":6.7,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Debian","score":7.4,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N","exploitability":7.2,"impact":6.7,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":7.4,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N","exploitability":null,"impact":null,"computed":false},{"version":"2.0","versionLabel":"v2.0","source":"NVD","score":4.3,"severity":"medium","vector":"AV:N/AC:M/Au:N/C:P/I:N/A:N","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.01477,"percentile":0.7349,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":0,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.01477},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.01426,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.01426,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.01426,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.01426,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.01426,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.01477,"percentile":0.7349}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.01477,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.01477,"percentile":0.7349}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[],"affected":[{"vendor":"debian","product":"firefox-esr","name":"firefox-esr","label":"firefox-esr","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/firefox-esr","purlType":"deb","versions":[{"text":"< 78.10.0esr-1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 78.10.0esr-1","eol":null,"hubHref":null},{"vendor":"debian","product":"thunderbird","name":"thunderbird","label":"thunderbird","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/thunderbird","purlType":"deb","versions":[{"text":"< 1:78.10.0-1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 1:78.10.0-1","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"firefox","name":"firefox","label":"firefox","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/firefox","purlType":"deb","versions":[{"text":"< 85.0+build1-0ubuntu0.16.04.1","noFixRecorded":false,"fixedIn":null},{"text":"< 85.0+build1-0ubuntu0.18.04.1","noFixRecorded":false,"fixedIn":null},{"text":"< 85.0+build1-0ubuntu0.20.04.1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 85.0+build1-0ubuntu0.16.04.1 | < 85.0+build1-0ubuntu0.18.04.1 | < 85.0+build1-0ubuntu0.20.04.1","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"mozjs38","name":"mozjs38","label":"mozjs38","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/mozjs38","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"mozjs52","name":"mozjs52","label":"mozjs52","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/mozjs52","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"mozjs68","name":"mozjs68","label":"mozjs68","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/mozjs68","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"mozjs78","name":"mozjs78","label":"mozjs78","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/mozjs78","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"thunderbird","name":"thunderbird","label":"thunderbird","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/thunderbird","purlType":"deb","versions":[{"text":"< 1:78.11.0+build1-0ubuntu0.18.04.2","noFixRecorded":false,"fixedIn":null},{"text":"< 1:78.11.0+build1-0ubuntu0.20.04.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 1:78.11.0+build1-0ubuntu0.18.04.2 | < 1:78.11.0+build1-0ubuntu0.20.04.2","eol":null,"hubHref":null},{"vendor":"debian","product":"debian_linux","name":"debian linux","label":"debian_linux","ecosystem":null,"cpePart":"o","purl":null,"purlType":null,"versions":[{"text":"9.0","noFixRecorded":false,"fixedIn":null},{"text":"10.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"9.0 | 10.0","eol":{"isEol":true,"eolDate":"2022-07-01T00:00:00.000Z","matchMethod":"cpe","cycle":{"name":"9","label":"9 (Stretch)","eolFrom":"2022-07-01T00:00:00.000Z","isLts":false,"isMaintained":true,"latestVersion":"9.13"},"product":{"name":"debian","label":"Debian","category":"os"}},"hubHref":"/vendor/debian/debian_linux"},{"vendor":"mozilla","product":"firefox","name":"Firefox","label":"firefox","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"< 85","noFixRecorded":false,"fixedIn":null},{"text":"< 85.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 85 | < 85.0","eol":{"isEol":null,"eolDate":null,"matchMethod":"cpe","cycle":null,"product":{"name":"firefox","label":"Firefox","category":"app"}},"hubHref":"/vendor/mozilla/firefox"}],"affectedCount":10,"eol":{"hasEol":true,"count":1},"references":[{"url":"https://www.mozilla.org/security/advisories/mfsa2021-03/","label":"www.mozilla.org/security/advisories/mfsa2021-03/","hostname":"www.mozilla.org","tags":["X Refsource MISC","Release Notes","Vendor Advisory"]},{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1677940","label":"bugzilla.mozilla.org/show_bug.cgi?id=1677940","hostname":"bugzilla.mozilla.org","tags":["X Refsource MISC","Issue Tracking","Permissions Required","Vendor Advisory"]},{"url":"https://www.debian.org/security/2021/dsa-4895","label":"www.debian.org/security/2021/dsa-4895","hostname":"www.debian.org","tags":["Vendor Advisory","X Refsource DEBIAN","Third Party Advisory"]},{"url":"https://lists.debian.org/debian-lts-announce/2021/04/msg00019.html","label":"lists.debian.org/debian-lts-announce/2021/04/msg00019.html","hostname":"lists.debian.org","tags":["Mailing List","X Refsource MLIST","Third Party Advisory"]},{"url":"https://www.debian.org/security/2021/dsa-4897","label":"www.debian.org/security/2021/dsa-4897","hostname":"www.debian.org","tags":["Vendor Advisory","X Refsource DEBIAN","Third Party Advisory"]},{"url":"https://lists.debian.org/debian-lts-announce/2021/04/msg00020.html","label":"lists.debian.org/debian-lts-announce/2021/04/msg00020.html","hostname":"lists.debian.org","tags":["Mailing List","X Refsource MLIST","Third Party Advisory"]},{"url":"https://security.gentoo.org/glsa/202104-10","label":"security.gentoo.org/glsa/202104-10","hostname":"security.gentoo.org","tags":["Vendor Advisory","X Refsource GENTOO","Third Party Advisory"]},{"url":"https://security.gentoo.org/glsa/202104-09","label":"security.gentoo.org/glsa/202104-09","hostname":"security.gentoo.org","tags":["Vendor Advisory","X Refsource GENTOO","Third Party Advisory"]},{"url":"https://ubuntu.com/security/CVE-2021-23961","label":"ubuntu.com/security/CVE-2021-23961","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://www.mozilla.org/en-US/security/advisories/mfsa2021-03/#CVE-2021-23961","label":"www.mozilla.org/en-US/security/advisories/mfsa2021-03/","hostname":"www.mozilla.org","tags":["REPORT"]},{"url":"https://ubuntu.com/security/notices/USN-4717-1","label":"ubuntu.com/security/notices/USN-4717-1","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://ubuntu.com/security/notices/USN-4995-1","label":"ubuntu.com/security/notices/USN-4995-1","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://ubuntu.com/security/notices/USN-4995-2","label":"ubuntu.com/security/notices/USN-4995-2","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-23961","label":"www.cve.org/CVERecord?id=CVE-2021-23961","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2021-23961","label":"security-tracker.debian.org/tracker/CVE-2021-23961","hostname":"security-tracker.debian.org","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":["DLA-2632-1","DLA-2633-1","DSA-4895-1","DSA-4897-1","MGASA-2021-0198","MGASA-2021-0199","OPENSUSE-SU-2021:0621-1","OPENSUSE-SU-2021:0644-1","OPENSUSE-SU-2024:10600-1","OPENSUSE-SU-2024:10601-1","OPENSUSE-SU-2024:14572-1","RHSA-2021:1350","RHSA-2021:1351","RHSA-2021:1352","RHSA-2021:1353","RHSA-2021:1360","RHSA-2021:1361","RHSA-2021:1362","RHSA-2021:1363","SUSE-SU-2021:1307-1","SUSE-SU-2021:1325-1","SUSE-SU-2021:1432-1","SUSE-SU-2021:1433-1","SUSE-SU-2021:14708-1","USN-4717-1","USN-4995-1","USN-4995-2"],"duplicates":[],"related":["OPENSUSE-SU-2021:0621-1","OPENSUSE-SU-2021:0644-1","OPENSUSE-SU-2024:10600-1","OPENSUSE-SU-2024:10601-1","OPENSUSE-SU-2024:14572-1","SUSE-SU-2021:1307-1","SUSE-SU-2021:1325-1","SUSE-SU-2021:1432-1","SUSE-SU-2021:1433-1","SUSE-SU-2021:14708-1","USN-4717-1","USN-4995-1","USN-4995-2"]},"timeline":[{"kind":"published","date":"2021-02-26T02:02:52.000Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2024-08-03T19:14:09.837Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":30,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-20T01:11:08.920Z","stale":false,"partial":false}}