What’s Vulnerable › Vulnerabilities

CVE-2026-8971: Same-origin policy bypass in the Networking: JAR component

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-19 · updated 2026-07-23
• Weakness: CWE-346

Description

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

Affected products

• Mozilla Firefox: before 151.0.0 — fixed in 151.0.0
• Mozilla Thunderbird: before 151.0.0 — fixed in 151.0.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 151.0.0; Mozilla Thunderbird 151.0.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2032604
• https://www.mozilla.org/security/advisories/mfsa2026-46/
• https://www.mozilla.org/security/advisories/mfsa2026-50/

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