CVE-2021-23978

Mozilla developers reported memory safety bugs present in Firefox 85 and Firefox ESR 78.7. 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 < 86, Thunderbird < 78.8, and Firefox ESR < 78.8.

• CWE-787

• https://bugzilla.mozilla.org/buglist.cgi?bug_id=786797%2C1682928%2C1687391%2C1687597Broken Link, Issue Tracking, Vendor Advisory
• https://lists.debian.org/debian-lts-announce/2021/03/msg00000.htmlMailing List, Third Party Advisory
• https://security.gentoo.org/glsa/202104-09Third Party Advisory
• https://security.gentoo.org/glsa/202104-10Third Party Advisory
• https://www.debian.org/security/2021/dsa-4866Third Party Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-07/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-08/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-09/Release Notes, Vendor Advisory
• https://bugzilla.mozilla.org/buglist.cgi?bug_id=786797%2C1682928%2C1687391%2C1687597Broken Link, Issue Tracking, Vendor Advisory
• https://lists.debian.org/debian-lts-announce/2021/03/msg00000.htmlMailing List, Third Party Advisory
• https://security.gentoo.org/glsa/202104-09Third Party Advisory
• https://security.gentoo.org/glsa/202104-10Third Party Advisory
• https://www.debian.org/security/2021/dsa-4866Third Party Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-07/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-08/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-09/Release Notes, Vendor Advisory

Published

Feb 26, 2021

Last Modified

Jun 17, 2026

Status

Modified

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