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Fencer Vulns
medium 5.3

CVE-2019-9801 json

Firefox will accept any registered Program ID as an external protocol handler and offer to launch this local application when given a match…

published 2019-04-26 7 y ago modified 2026-06-17 4 mo ago also EUVD-2019-19163

cvss
5.3
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 70%
public exploits
0
none known

Summary

Firefox will accept any registered Program ID as an external protocol handler and offer to launch this local application when given a matching URL on Windows operating systems. This should only happen if the program has specifically registered itself as a "URL Handler" in the Windows registry. *Note: This issue only affects Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

Patch / fix

  • Mozilla Thunderbird 60.6
  • Mozilla Firefox ESR 60.6
  • Mozilla Firefox 66
  • MozillaFirefox SLE Module for Desktop Applications 15 60.6.1-3.29.3
  • MozillaThunderbird SLE Workstation Extension 15 60.6.1-3.28.1
  • MozillaFirefox SLES for SAP 12 SP4, SLES for SAP 12 SP3, SLES for SAP 12 SP2 +13 more 60.6.1esr-109.63.2

suse advisories SUSE-SU-2019:0871-1SUSE-SU-2019:0853-1SUSE-SU-2019:0852-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2
  • MozillaThunderbird openSUSE Leap 15.0 60.6.1-lp150.3.37.1
  • MozillaThunderbird Package Hub 12 60.6.1-82.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1openSUSE-SU-2019:1162-1openSUSE-SU-2019:1126-1

  • firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +12 more 60.6.1-r0

alpine advisories ALPINE-CVE-2019-9801

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2019-9801 updated cvss 6.1

Mozilla: Windows programs that are not 'URL Handlers' are exposed to web content

  • Red Hat Enterprise Linux 6 firefox, thunderbird Red Hat Enterprise Linux 7 firefox, thunderbird
    not affected: vulnerable code not present

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

1.31% chance of exploitation in the next 30 days, higher than 70% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 5.3 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Affected products

  • Mozilla Thunderbird
  • Mozilla Firefox ESR
  • Mozilla Firefox

Classification

Weakness
  • CWE-20 Improper Input Validation

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.