SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2016-5254

Use-after-free vulnerability in the nsXULPopupManager::KeyDown function in Mozilla Firefox before 48.0 and Firefox ESR 45.x before 45.3 allows attackers to execute arbitrary code or cause a denial of service (heap memory corruption and application…

CRITICAL 9.8EPSS 2.95%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (2.95%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

Use-after-free vulnerability in the nsXULPopupManager::KeyDown function in Mozilla Firefox before 48.0 and Firefox ESR 45.x before 45.3 allows attackers to execute arbitrary code or cause a denial of service (heap memory corruption and application crash) by leveraging keyboard access to use the Alt key during selection of top-level menu items.

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
2.95% probability · 87th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-416
Affected
mozilla/firefox · oracle/linux
Source
security@mozilla.org
EPSS trend
0%3%5%26 October 2026: 2.95%26 October 202626 October 2026

EPSS 3.0% since 26 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.