CVE-2026-8964

HIGHNVD 7.57.5—

7.5

Spoofing issue in the Popup Blocker component. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

CVSS v3: 7.5
EG Score: 7.5(high)
EPSS: 7.3%
KEV: Not listed

Published

May 19, 2026

Last Modified

May 20, 2026

References (3)

security@mozillahttps://bugzilla.mozilla.org/show_bug.cgi?id=2025170
security@mozillahttps://www.mozilla.org/security/advisories/mfsa2026-46/
security@mozillahttps://www.mozilla.org/security/advisories/mfsa2026-50/

Vendor Advisories for CVE-2026-8964(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

GHSA-x37c-vm4v-4wvx
GitHub Security AdvisoriesHigh
Spoofing issue in the Popup Blocker component. This vulnerability was fixed in Firefox 151.

Frequently asked(5)

What is CVE-2026-8964?

CVE-2026-8964 is a high vulnerability published on May 19, 2026. Spoofing issue in the Popup Blocker component. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

When was CVE-2026-8964 disclosed?

CVE-2026-8964 was first published in the National Vulnerability Database on May 19, 2026, with the most recent update on May 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2026-8964 actively exploited?

CVE-2026-8964 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 7.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2026-8964?

CVE-2026-8964 has a CVSS v3 base score of 7.5 (NVD).

How do I remediate CVE-2026-8964?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8964, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-8964

Explore →

Is Your Infrastructure Affected by CVE-2026-8964?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs

CVE-2026-8964

📅 Published

🔄 Last Modified

🔗 References (3)

📣 Vendor Advisories for CVE-2026-8964(1)

❓ Frequently asked(5)