SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2019-9804

In Firefox Developer Tools it is possible that pasting the result of the 'Copy as cURL' command into a command shell on macOS will cause the execution of unintended additional bash script commands if the URL was maliciously crafted.

CRITICAL 9.8EPSS 1.83%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (1.83%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

In Firefox Developer Tools it is possible that pasting the result of the 'Copy as cURL' command into a command shell on macOS will cause the execution of unintended additional bash script commands if the URL was maliciously crafted. This is the result of an issue with the native version of Bash on macOS. *Note: This issue only affects macOS. Other operating systems are unaffected.*. This vulnerability affects Firefox < 66.

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
1.83% probability · 79th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-78
Affected
mozilla/firefox
Source
security@mozilla.org
EPSS trend
0%3%5%26 October 2026: 1.83%26 October 202626 October 2026

EPSS 1.8% 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.