Attack Chain

1. An attacker crafts a malicious webpage or injects malicious code into a trusted website.
2. A user visits the malicious website or a compromised trusted website using a vulnerable version of Firefox.
3. The browser parses the malicious HTML/JavaScript code.
4. One of the vulnerabilities (memory corruption, use-after-free, etc.) is triggered during the parsing or rendering process.
5. The attacker gains control of the browser process.
6. The attacker leverages the gained control to execute arbitrary code on the user’s system.
7. The attacker installs malware, such as a keylogger or remote access trojan (RAT).
8. The attacker performs malicious activities, such as stealing sensitive data or establishing a command and control channel.

Impact

Successful exploitation of these vulnerabilities could lead to arbitrary code execution, potentially allowing an attacker to gain control of the affected system. This can lead to data theft, malware installation, and further compromise of the network. The scope of impact depends on the privileges of the user running the vulnerable Firefox version. Since Firefox is a widely used browser, a large number of users are potentially at risk if they do not apply the necessary updates.

Recommendation

• Upgrade Firefox to version 150.0.1 or later to patch the vulnerabilities (refer to Mozilla Foundation Security Advisory 2026-35).
• Upgrade Firefox ESR to version 140.10.1 or later to patch the vulnerabilities (refer to Mozilla Foundation Security Advisory 2026-36).
• Upgrade Firefox ESR to version 115.35.1 or later to patch the vulnerabilities (refer to Mozilla Foundation Security Advisory 2026-37).
• Deploy the “Detect Firefox Process Launching Suspicious Child Process” Sigma rule to identify potential exploitation attempts.