CVE-2026-8948

CRITICALNVD 9.19.1—

9.1

Same-origin policy bypass in the DOM: Networking component. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

CVSS v3: 9.1
EG Score: 9.1(high)
EPSS: 12.0%
KEV: Not listed

Published

May 19, 2026

Last Modified

May 20, 2026

Advisory Details (3)

Auto-updated May 19, 2026

No patch confirmed yet.

generic

Security Vulnerabilities fixed in Thunderbird 151 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-50/

generic

Security Vulnerabilities fixed in Firefox 151 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-46/

generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2038803

Vendor Advisories for CVE-2026-8948(1)

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

GHSA-j9gx-gpjh-cwc4
GitHub Security AdvisoriesCritical
Same-origin policy bypass in the DOM: Networking component. This vulnerability was fixed in...

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-942Permissive Cross-domain Policy with Untrusted Domains

Data Freshness Timeline

(refreshed 4× in last 7d / 7× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-05-27 13:40 UTCepss_batch
2026-05-26 13:44 UTCepss_batch
2026-05-26 07:18 UTCepss_batch
2026-05-21 22:43 UTCepss_batch
2026-05-20 22:38 UTCepss_batch
2026-05-20 11:42 UTCEG score recompute
2026-05-20 11:42 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2026-8948?

CVE-2026-8948 is a critical vulnerability published on May 19, 2026. Same-origin policy bypass in the DOM: Networking component. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

When was CVE-2026-8948 disclosed?

CVE-2026-8948 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-2026-8948 actively exploited?

CVE-2026-8948 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 12.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2026-8948?

CVE-2026-8948 has a CVSS v3 base score of 9.1 (NVD).

How do I remediate CVE-2026-8948?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8948, 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

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CVE-2026-8948

📅 Published

🔄 Last Modified

📋 Advisory Details (3)

Security Vulnerabilities fixed in Thunderbird 151 — Mozilla

Security Vulnerabilities fixed in Firefox 151 — Mozilla

Access Denied

📣 Vendor Advisories for CVE-2026-8948(1)

Weakness Classification(1)

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2026-8948?

Published

Last Modified

Advisory Details (3)

Vendor Advisories for CVE-2026-8948(1)

Frequently asked(5)