SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2017-5402

A use-after-free can occur when events are fired for a "FontFace" object after the object has been already been destroyed while working with fonts.

CRITICAL 9.8EPSS 2.84%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (2.84%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

A use-after-free can occur when events are fired for a "FontFace" object after the object has been already been destroyed while working with fonts. This results in a potentially exploitable crash. This vulnerability affects Firefox < 52, Firefox ESR < 45.8, Thunderbird < 52, and Thunderbird < 45.8.

CVSS 3.0
9.8 CRITICALCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
2.84% probability · 87th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-416
Affected
debian/debian linux · 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/thunderbird · mozilla/firefox
Source
security@mozilla.org
EPSS trend
0%3%5%27 October 2026: 2.84%27 October 202627 October 2026

EPSS 2.8% 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.

References

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