CVE-2018-5174

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.

7.5

CVSS

Severity: High

CVSS 3.0 •

CVSS 2.0 •

EPSS 0.54%

Vendor Advisory mozilla.org Vendor Advisory mozilla.org Vendor Advisory mozilla.org

Affected: Mozilla Thunderbird

Affected: Mozilla Thunderbird ESR

Affected: Mozilla Firefox

Affected: Mozilla Firefox ESR

References

Link	Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=1447080	issue tracking permissions required third party advisory
https://www.mozilla.org/security/advisories/mfsa2018-13/	vendor advisory
https://www.mozilla.org/security/advisories/mfsa2018-11/	vendor advisory
http://www.securitytracker.com/id/1040896	vdb entry third party advisory
https://www.mozilla.org/security/advisories/mfsa2018-12/	vendor advisory
http://www.securityfocus.com/bid/104136	vdb entry third party advisory

Frequently Asked Questions

What is the severity of CVE-2018-5174?: CVE-2018-5174 has been scored as a high severity vulnerability.
How to fix CVE-2018-5174?: To fix CVE-2018-5174, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2018-5174 being actively exploited in the wild?: As for now, there are no information to confirm that CVE-2018-5174 is being actively exploited. According to its EPSS score, there is a ~1% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2018-5174?: CVE-2018-5174 affects Mozilla Thunderbird, Mozilla Thunderbird ESR, Mozilla Firefox, Mozilla Firefox ESR.