What’s Vulnerable › Vulnerabilities

CVE-2026-3846: Same-origin policy bypass in the CSS Parsing and Computation component

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-10 · updated 2026-06-17
• Weakness: CWE-346

Description

Same-origin policy bypass in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 148.0.2.

Affected products

• Mozilla Firefox: before 148.0.2 — fixed in 148.0.2

How to fix

Upgrade to a fixed version: Mozilla Firefox 148.0.2. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2018400
• https://www.mozilla.org/security/advisories/mfsa2026-19/

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