CVE-2026-16381

CRITICAL 9.1

Same-origin policy bypass in the Networking: DNS component

CVSS Score

9.1

EPSS Score

0.0%

EPSS Percentile

0th

Same-origin policy bypass in the Networking: DNS component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

Vendor	mozilla
Product	firefox
Ecosystems	Browser JavaScript
Industries	Technology
Published	Jul 21, 2026
Last Updated	Jul 22, 2026

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Affected Versions

Mozilla / Firefox

All versions affected

Mozilla / Thunderbird

All versions affected

References

NVD ↗ CVE.org ↗ EPSS Data ↗

bugzilla.mozilla.org: https://bugzilla.mozilla.org/show_bug.cgi?id=2041001 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-68/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-70/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-71/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-72/

Credits

Rintaro Kawasugi