CVE-2019-11728: Mozilla Firefox

Medium severity, CVSS 4.7. EPSS: 1.1% chance of exploitation in the next 30 days.

The HTTP Alternative Services header, Alt-Svc, can be used by a malicious site to scan all TCP ports of any host that the accessible to a user when web content is loaded. This vulnerability affects Firefox < 68.

Affected products

• Mozilla Firefox: before 68.0 (fixed in 68.0)
• Opensuse Leap: version 15.0 only; version 15.1 only

Published 2019-07-23. Last modified 2026-06-17.