Full Report
Mozilla security advisory (AV26-478)
Analysis Summary
# Vulnerability: Multiple Vulnerabilities in Mozilla Firefox Products (AV26-478)
## CVE Details
- **CVE ID:** CVE-2026-XXXX (Specific IDs are typically distributed across MFSA 2026-46, 47, and 48)
- **CVSS Score:** 7.5 - 9.8 (Estimated Range based on typical Mozilla Critical/High updates)
- **CWE:** Commonly includes CWE-416 (Use After Free), CWE-787 (Out-of-bounds Write), and CWE-119 (Memory Corruption).
## Affected Systems
- **Products:**
- Mozilla Firefox
- Mozilla Firefox ESR (Extended Support Release)
- **Versions:**
- Firefox versions prior to 151
- Firefox ESR versions prior to 115.36
- Firefox ESR versions prior to 140.11
- **Configurations:** Default installations of the browser on Windows, macOS, and Linux.
## Vulnerability Description
While the summary advisory (AV26-478) acts as a high-level notification, the underlying Mozilla Foundation Security Advisories (MFSA) address multiple security flaws. These typically involve memory safety bugs within the browser engine (SpiderMonkey or Gecko) and potential logic errors. If exploited, these flaws allow for memory corruption that could lead to arbitrary code execution within the context of the browser process.
## Exploitation
- **Status:** Not currently reported as exploited in the wild (refer to specific MFSA links for targeted 0-day updates).
- **Complexity:** Medium to High.
- **Attack Vector:** Network (Remote). Usually requires a victim to visit a specially crafted malicious website.
## Impact
- **Confidentiality:** High (Potential to steal cookies, session data, or local files).
- **Integrity:** High (Potential to execute unauthorized code on the host).
- **Availability:** High (Potential for application crashes and denial of service).
## Remediation
### Patches
Mozilla recommends updating to the following versions immediately:
- **Firefox:** 151 or newer.
- **Firefox ESR:** 115.36 or newer.
- **Firefox ESR:** 140.11 or newer.
### Workarounds
- There are no direct workarounds that maintain full browser functionality.
- General mitigation: Enable **"Strict" Mode** in Tracking Protection and ensure **HTTPS-Only Mode** is active to reduce attack surface.
## Detection
- **Indicators of Compromise:** Unusual browser crashes, unexplained outbound network connections to unknown IPs, or unauthorized modifications to browser profile settings.
- **Detection methods:** Enterprise environments can use EDR (Endpoint Detection and Response) tools to monitor for child processes spawned by `firefox.exe` (such as `cmd.exe` or `powershell.exe`).
## References
- **Vendor Advisories:**
- hxxps[://]www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-46/
- hxxps[://]www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-47/
- hxxps[://]www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-48/
- **Security Bulletin:**
- hxxps[://]www[.]cyber[.]gc[.]ca/en/alerts-advisories/mozilla-security-advisory-av26-478