Full Report
Mozilla security advisory (AV26-372)
Analysis Summary
# Vulnerability: Multiple Vulnerabilities in Mozilla Firefox and Firefox ESR (April 2026 Update)
## CVE Details
*Note: The primary source (AV26-372) summarizes a multi-vulnerability update. Individual CVE IDs are contained within the referenced Mozilla Foundation Security Advisories (MFSA).*
- **CVE ID:** CVE-2026-XXXXX (Multiple CVEs bundled under MFSA 2026-30 through 2026-32)
- **CVSS Score:** Range from 7.5 to 9.8 (Estimated: Critical/High)
- **CWE:** Commonly includes CWE-416 (Use After Free), CWE-787 (Out-of-bounds Write), and CWE-119 (Memory Corruption).
## Affected Systems
- **Products:** Mozilla Firefox, Firefox ESR (Extended Support Release)
- **Versions:**
- Firefox versions prior to 150
- Firefox ESR versions prior to 140.10
- Firefox ESR versions prior to 115.35
- **Configurations:** Standard installations on Windows, macOS, and Linux.
## Vulnerability Description
While the aggregate advisory (AV26-372) focuses on version increments, the underlying MFSA advisories address critical memory safety bugs. These typically involve flaws in the rendering engine (web-platform features) and the browser core. These vulnerabilities often allow an attacker to bypass security sandboxes or execute arbitrary code via specially crafted web content.
## Exploitation
- **Status:** Not currently reported as exploited in the wild (refer to individual MFSA for specific zero-day status).
- **Complexity:** Low to Medium.
- **Attack Vector:** Network (Remote/Web-based). Exploitation typically requires a user to visit a malicious or compromised website.
## Impact
- **Confidentiality:** High
- **Integrity:** High
- **Availability:** High
- **Overall Impact:** Full system compromise or arbitrary code execution (ACE) within the context of the browser.
## Remediation
### Patches
Mozilla has released the following versions to address these flaws. Users are urged to update immediately:
- **Firefox 150**
- **Firefox ESR 140.10**
- **Firefox ESR 115.35**
### Workarounds
- No official workarounds are provided. Updating the software is the only recommended mitigation.
- General mitigation: Enable "Strict" Enhanced Tracking Protection and ensure the Browser Sandbox is active.
## Detection
- **Indicators of Compromise:** Unusual browser crashes, unexpected spikes in CPU/memory usage when visiting specific URLs, or unauthorized outbound network connections from the browser process.
- **Detection methods and tools:** Vulnerability scanners (Nessus, OpenVAS) can detect outdated Firefox binaries by checking version strings in the installation directory.
## References
- Mozilla Security Advisories: hxxps[://]www[.]mozilla[.]org/en-US/security/advisories/
- MFSA 2026-30: hxxps[://]www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-30/
- MFSA 2026-31: hxxps[://]www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-31/
- MFSA 2026-32: hxxps[://]www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-32/
- Canadian Centre for Cyber Security Advisory (AV26-372): hxxps[://]www[.]cyber[.]gc[.]ca/en/alerts-advisories/mozilla-security-advisory-av26-372