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CVE-2026-8948

Mozilla Firefox cross-site scripting (XSS)

9.1 CRITICALEPSS 0.45%
  1. Published19 May 2026

Description

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

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

Mozilla Firefox< 151.0.0
Mozilla Thunderbird< 151.0.0

Remediation

Fixed in
Mozilla Firefox≥ 151.0.0
Mozilla Thunderbird≥ 151.0.0

References

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Frequently asked

Is CVE-2026-8948 being actively exploited?

CVE-2026-8948 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.45%.

How severe is CVE-2026-8948?

CVE-2026-8948 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.45% probability of exploitation.

Which products are affected by CVE-2026-8948?

Affected products include Mozilla Firefox, Mozilla Thunderbird.

How do I fix CVE-2026-8948?

Upgrade affected software to a fixed version, for example Mozilla Firefox 151.0.0, Mozilla Thunderbird 151.0.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-8948 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.