SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2017-5451

This vulnerability affects Thunderbird < 52.1, Firefox ESR < 52.1, and Firefox < 53.

MEDIUM 4.3EPSS 1.48%

Does this matter?

Lower severity and a low EPSS score (1.48%). Track it; it rarely justifies an emergency change on its own.

Description

A mechanism to spoof the addressbar through the user interaction on the addressbar and the "onblur" event. The event could be used by script to affect text display to make the loaded site appear to be different from the one actually loaded within the addressbar. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 52.1, and Firefox < 53.

CVSS 3.0
4.3 MEDIUMCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
EPSS
1.48% probability · 74th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-20
Affected
redhat/enterprise linux · redhat/enterprise linux desktop · redhat/enterprise linux server · redhat/enterprise linux server aus · redhat/enterprise linux server eus · redhat/enterprise linux workstation · mozilla/firefox · mozilla/thunderbird
Source
security@mozilla.org
EPSS trend
0%3%5%27 October 2026: 1.48%27 October 202627 October 2026

EPSS 1.5% 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.