SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2018-5115

This vulnerability affects Firefox < 58.

HIGH 7.5EPSS 2.43%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (2.43%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

If an HTTP authentication prompt is triggered by a background network request from a page or extension, it is displayed over the currently loaded foreground page. Although the prompt contains the real domain making the request, this can result in user confusion about the originating site of the authentication request and may cause users to mistakenly send private credential information to a third party site. This vulnerability affects Firefox < 58.

CVSS 3.0
7.5 HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
2.43% probability · 84th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-200
Affected
mozilla/firefox · canonical/ubuntu linux
Source
security@mozilla.org
EPSS trend
0%3%5%27 October 2026: 2.43%27 October 202627 October 2026

EPSS 2.4% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.