SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2017-5434

A use-after-free vulnerability occurs when redirecting focus handling which results in a potentially exploitable crash.

CRITICAL 9.8EPSS 3.50%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (3.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

A use-after-free vulnerability occurs when redirecting focus handling which results in a potentially exploitable crash. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 45.9, Firefox ESR < 52.1, and Firefox < 53.

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
3.50% probability · 89th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-416
Affected
redhat/enterprise linux desktop · redhat/enterprise linux server · redhat/enterprise linux workstation · debian/debian linux · mozilla/firefox · mozilla/thunderbird
Source
security@mozilla.org
EPSS trend
0%3%5%27 October 2026: 3.50%27 October 202627 October 2026

EPSS 3.5% 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.

References

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