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Fencer Intel
high 7.5

CVE-2018-5174 json

In the Windows 10 April 2018 Update, Windows Defender SmartScreen honors the "SEE_MASK_FLAG_NO_UI" flag associated with downloaded files an…

published 2018-06-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-16959

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

In the Windows 10 April 2018 Update, Windows Defender SmartScreen honors the "SEE_MASK_FLAG_NO_UI" flag associated with downloaded files and will not show any UI. Files that are unknown and potentially dangerous will be allowed to run because SmartScreen will not prompt the user for a decision, and if the user is offline all files will be allowed to be opened because Windows won't prompt the user to ask what to do. Firefox incorrectly sets this flag when downloading files, leading to less secure behavior from SmartScreen. Note: this issue only affects Windows 10 users running the April 2018 update or later. It does not affect other Windows users or other operating systems. This vulnerability affects Thunderbird < 52.8, Thunderbird ESR < 52.8, Firefox < 60, and Firefox ESR < 52.8.

Patch / fix

  • Mozilla Thunderbird 52.8
  • Mozilla Thunderbird ESR 52.8
  • Mozilla Firefox 60
  • Mozilla Firefox ESR 52.8
  • MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +17 more 68.2.0-109.95.2
  • MozillaFirefox SLES 12 SP3, SLES 12 SP2-BCL, SLED 12 SP3 +9 more 52.8.0esr-109.31.2
  • MozillaFirefox SLES for SAP 11 SP4, SLES 11 SP4, SLES 11 SP3-TERADATA +3 more 52.8.0esr-72.32.1

suse advisories SUSE-SU-2019:2872-1SUSE-SU-2018:1334-2SUSE-SU-2018:1334-1SUSE-SU-2018:1319-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2
  • MozillaThunderbird openSUSE Tumbleweed 91.1.1-1.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1openSUSE-SU-2024:10601-1

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-2018-5174 updated cvss 7.5

Mozilla: Windows Defender SmartScreen UI runs with less secure behavior for downloaded files in Windows 10 April 2018 Update

  • 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

1.81% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Affected products

  • Mozilla Thunderbird
  • Mozilla Thunderbird ESR
  • Mozilla Firefox
  • Mozilla Firefox ESR

References

Sources

Fencer Intel 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.