{"id":"CVE-2021-23964","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-23964","generatedAt":"2026-10-27T23:37:24.544Z","title":"Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.","description":"Mozilla developers reported memory safety bugs present in Firefox 84 and Firefox ESR 78.6. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 85, Thunderbird < 78.7, and Firefox ESR < 78.7.","published":"2021-02-26T16:15:12.000Z","lastModified":"2026-06-17T03:39:05.000Z","status":"Modified","sourceIdentifier":"security@mozilla.org","cvss":{"version":"3.1","score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"},"cwe":["CWE-787"],"affected":["mozilla/firefox","mozilla/firefox esr","mozilla/thunderbird"],"epss":{"score":0.01361,"percentile":0.71556,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (1.36%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://bugzilla.mozilla.org/buglist.cgi?bug_id=1662507%2C1666285%2C1673526%2C1674278%2C1674835%2C1675097%2C1675844%2C1675868%2C1677590%2C1677888%2C1680410%2C1681268%2C1682068%2C1682938%2C1683736%2C1685260%2C1685925","tags":["Broken Link","Issue Tracking","Vendor Advisory"],"source":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2021-03/","tags":["Release Notes","Vendor Advisory"],"source":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2021-04/","tags":["Release Notes","Vendor Advisory"],"source":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2021-05/","tags":["Release Notes","Vendor Advisory"],"source":"security@mozilla.org"},{"url":"https://bugzilla.mozilla.org/buglist.cgi?bug_id=1662507%2C1666285%2C1673526%2C1674278%2C1674835%2C1675097%2C1675844%2C1675868%2C1677590%2C1677888%2C1680410%2C1681268%2C1682068%2C1682938%2C1683736%2C1685260%2C1685925","tags":["Broken Link","Issue Tracking","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.mozilla.org/security/advisories/mfsa2021-03/","tags":["Release Notes","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.mozilla.org/security/advisories/mfsa2021-04/","tags":["Release Notes","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.mozilla.org/security/advisories/mfsa2021-05/","tags":["Release Notes","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-23964","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}