CVE-2026-15719: Site isolation issue in the DOM: Navigation component

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-14 · updated 2026-07-22

Description

We are aware that exploit code for this is public however we are not aware of any attacks in the wild abusing this flaw. This vulnerability was fixed in Firefox 152.0.6, Firefox ESR 115.38, Firefox ESR 140.13, and Thunderbird 140.13.

Affected products

Mozilla Firefox: before 152.0.6 — fixed in 152.0.6

How to fix

Upgrade to a fixed version: Mozilla Firefox 152.0.6. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2043820
https://www.mozilla.org/security/advisories/mfsa2026-67/
https://www.mozilla.org/security/advisories/mfsa2026-69/
https://www.mozilla.org/security/advisories/mfsa2026-70/
https://www.mozilla.org/security/advisories/mfsa2026-72/

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