CVE-2026-8950
Same-origin policy bypass in browser HTTP component.
Is CVE-2026-8950 being exploited?
Not confirmed. CVE-2026-8950 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.19% probability of exploitation in the next 30 days.
How severe is CVE-2026-8950?
CVE-2026-8950 is rated Critical with a CVSS score of 9.3. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-8950?
Yes. A fix has been recorded for CVE-2026-8950. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-8950 affect?
CVE-2026-8950 affects Firefox, Thunderbird. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-8950?
Upgrade to Firefox 151+/ESR 140.11 and Thunderbird 151+/140.11
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Bypass of same-origin policy enabling cross-origin data access via the browser's Networking: HTTP stack; risk of data exposure.
Immediate action required