mozilla firefox CVE-2026-118021 vulnerability in Mozilla Products
Published on October 27, 2026

Sandbox escape due to use-after-free in the XPCOM component

product logo product logo
Sandbox escape due to use-after-free in the XPCOM component. This vulnerability was fixed in Firefox 159 and Thunderbird 159.

NVD

Vulnerability Analysis

CVE-2026-118021 can be exploited with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
REQUIRED
Scope:
UNCHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
HIGH
Availability Impact:
HIGH

Weakness Type

What is a Dangling pointer Vulnerability?

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

CVE-2026-118021 has been classified to as a Dangling pointer vulnerability or weakness.


Products Associated with CVE-2026-118021

stack.watch emails you whenever new vulnerabilities are published in Mozilla Firefox or Mozilla Thunderbird. Just hit a watch button to start following.

Mozilla Firefox
 
Mozilla Thunderbird
 

Affected Versions

Mozilla Firefox: Mozilla Thunderbird: