CVE-2018-5174

moderate-risk
Published 2018-06-11

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.

Do I need to act?

-
0.54% chance of exploitation
EPSS score — low exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
7
CVSS 7.5/10 High
NETWORK / LOW complexity

Affected Products (3)

Affected Vendors

Mozilla

References (12)

Third Party Advisory http://www.securityfocus.com/bid/104136
Third Party Advisory http://www.securitytracker.com/id/1040896
Issue Tracking https://bugzilla.mozilla.org/show_bug.cgi?id=1447080
Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2018-11/
Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2018-12/
Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2018-13/
Third Party Advisory http://www.securityfocus.com/bid/104136
Third Party Advisory http://www.securitytracker.com/id/1040896
Issue Tracking https://bugzilla.mozilla.org/show_bug.cgi?id=1447080
Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2018-11/
Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2018-12/
Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2018-13/
37
/ 100
moderate-risk
Severity 26/34 · High
Exploitability 2/34 · Minimal
Exposure 9/34 · Low