CVE-2018-5121

Publication date 11 June 2018

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

Low descenders on some Tibetan characters in several fonts on OS X are clipped when rendered in the addressbar. When used as part of an Internationalized Domain Name (IDN) this can be used for domain name spoofing attacks. Note: This attack only affects OS X operating systems. Other operating systems are unaffected. This vulnerability affects Firefox < 58.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
firefox	17.10 artful	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release
thunderbird	17.10 artful	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release

Notes

chrisccoulson

OS X only

Severity score breakdown

CVSS version: CVSS v3.0

Base score 5.3 · Medium

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	Low
Availability impact	None

Scores

Parameter	Value
Base score	5.3 · Medium
Exploitability score	-
Impact score	-

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N