SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2019-11757

This resulted in a use-after-free and a potentially exploitable crash.

HIGH 8.8EPSS 1.33%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (1.33%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

When following the value's prototype chain, it was possible to retain a reference to a locale, delete it, and subsequently reference it. This resulted in a use-after-free and a potentially exploitable crash. This vulnerability affects Firefox < 70, Thunderbird < 68.2, and Firefox ESR < 68.2.

CVSS 3.1
8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS
1.33% probability · 71th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-416
Affected
mozilla/firefox · mozilla/firefox esr · mozilla/thunderbird · canonical/ubuntu linux
Source
security@mozilla.org
EPSS trend
0%3%5%27 October 2026: 1.33%27 October 202627 October 2026

EPSS 1.3% 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.