Description
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.
Published: 2018-06-11
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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Advisories
Source ID Title
EUVD EUVD EUVD-2018-16959 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.
History

Tue, 25 Nov 2025 18:00:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
Vendors & Products Mozilla firefox Esr

Subscriptions

Microsoft Windows 10
Mozilla Firefox Thunderbird Thunderbird Esr
cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2024-08-05T05:26:47.099Z

Reserved: 2018-01-03T00:00:00.000Z

Link: CVE-2018-5174

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2018-06-11T21:29:15.983

Modified: 2025-11-25T17:50:16.803

Link: CVE-2018-5174

cve-icon Redhat

Severity : Moderate

Publid Date: 2018-05-09T00:00:00Z

Links: CVE-2018-5174 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses