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Fencer Vulns
medium 4.7

CVE-2019-11728 json

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 u…

published 2019-07-23 7 y ago modified 2026-06-17 4 mo ago also EUVD-2019-3398

cvss
4.7
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 66%
public exploits
0
none known

Summary

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.

Patch / fix

  • Mozilla Firefox 68
  • firefox Ubuntu 16.04 LTS 68.0+build3-0ubuntu0.16.04.1
  • firefox Ubuntu 18.04 LTS 68.0+build3-0ubuntu0.18.04.1

ubuntu advisories UBUNTU-CVE-2019-11728

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +18 more 68.1.0-109.89.1
  • MozillaFirefox-branding-SLE SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +16 more 68-32.8.1
  • MozillaFirefox SLE Module for Desktop Applications 15 SP1, SLE Module for Desktop Applications 15 68.1.0-3.54.2
  • MozillaFirefox-branding-SLE SLE Module for Desktop Applications 15 SP1, SLE Module for Desktop Applications 15 68-4.8.5
  • MozillaThunderbird SLE Workstation Extension 15 SP1, SLE Workstation Extension 15 68.1.1-3.51.1
  • firefox-atk SLES 11 SP4-LTSS 2.26.1-2.8.4
  • mozilla-nss SLES 11 SP4-LTSS 3.45-38.9.3
  • firefox-gtk3 SLES 11 SP4-LTSS 3.10.9-2.15.3

suse advisories SUSE-SU-2019:14246-1SUSE-SU-2019:2620-1SUSE-SU-2019:2545-1SUSE-SU-2019:2515-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2
  • MozillaFirefox openSUSE Leap 15.0 68.1.0-lp150.3.66.1
  • MozillaFirefox openSUSE Leap 15.1 68.1.0-lp151.2.14.1
  • MozillaThunderbird openSUSE Leap 15.1 68.1.1-lp151.2.13.1
  • enigmail openSUSE Leap 15.1 2.1.2-lp151.2.6.1
  • MozillaThunderbird openSUSE Leap 15.0 68.1.1-lp150.3.51.1
  • enigmail openSUSE Leap 15.0 2.1.2-lp150.34.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1openSUSE-SU-2019:2260-1openSUSE-SU-2019:2251-1openSUSE-SU-2019:2249-1openSUSE-SU-2019:2248-1

  • firefox Arch Linux 68.0-1

arch linux advisories AVG-1002

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-11728 updated cvss 4.7

Mozilla: Port scanning through Alt-Svc header

  • Red Hat Enterprise Linux 5 firefox
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 6 firefox Red Hat Enterprise Linux 7 firefox Red Hat Enterprise Linux 8 firefox
    affected: no fix planned “Will not fix”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.12% chance of exploitation in the next 30 days, higher than 66% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 4.7 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N

Affected products

  • Mozilla Firefox

Classification

Weakness
  • CWE-668 Exposure of Resource to Wrong Sphere

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.