CVE-2021-23999

If a Blob URL was loaded through some unusual user interaction, it could have been loaded by the System Principal and granted additional privileges that should not be granted to web content. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

• CWE-269
• CWE-697

• https://bugzilla.mozilla.org/show_bug.cgi?id=1691153Exploit, Issue Tracking, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-14/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-15/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-16/Release Notes, Vendor Advisory
• https://bugzilla.mozilla.org/show_bug.cgi?id=1691153Exploit, Issue Tracking, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-14/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-15/Release Notes, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2021-16/Release Notes, Vendor Advisory

Published

Jun 24, 2021

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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