Firefox Vulnerabilities in Daily Threat Briefings

Overview of Firefox Vulnerabilities in Daily Threat Briefings

The user's summary reflects ongoing concerns in cybersecurity threat briefings (e.g., from CISA, Krebs on Security, and vendor alerts) about multiple vulnerabilities in Mozilla Firefox, particularly memory safety issues that could result in denial-of-service (DoS) crashes or arbitrary code execution. These flaws are often highlighted due to their potential for exploitation in phishing campaigns, where attackers lure users via emails or malicious links to sites that trigger the vulnerabilities on unpatched browsers. While some zero-days have been actively exploited in controlled environments like the Pwn2Own Berlin 2025 contest, real-world phishing attacks typically target outdated installations by combining social engineering with known exploits. Mozilla has released patches in recent updates, such as Firefox 141 (July 22, 2025) and Firefox 140 (June 24, 2025), but delayed updates leave users vulnerable. No classified widespread campaigns are confirmed as of July 24, 2025, but security firms warn of scanning activity and phishing lures exploiting similar browser flaws.Key facts from reports:

• Vulnerability Details:
  • Recent patches in Firefox 141 address clusters of memory safety bugs (e.g., CVE-2025-8044, CVE-2025-8034, CVE-2025-8040, CVE-2025-8035), which show evidence of memory corruption potentially exploitable for arbitrary code execution or DoS crashes. These are rated High severity and fixed in mfsa2025-56.
  • Firefox 140 (mfsa2025-51) fixed issues like use-after-free in FontFaceSet (CVE-2025-6424, potential code execution), URL parsing flaws enabling phishing on Android (CVE-2025-6428), and XSS via Content-Disposition bypass (CVE-2025-6430).
  • Earlier notable flaws: Zero-days CVE-2025-4918 and CVE-2025-4919 (out-of-bounds memory access in JS engine, exploited at Pwn2Own Berlin 2025 for code execution); CVE-2025-2857 (sandbox escape similar to exploited Chrome flaw).
• Exploitation Timeline: Zero-days from Pwn2Own (May 2025) were patched quickly but demonstrated RCE. Memory safety bugs in recent updates are presumed exploitable with effort, though no in-the-wild attacks confirmed beyond contest demos. Phishing campaigns often exploit outdated browsers by embedding malicious code in fake login pages or attachments.
• Impact and Targets: Affects Firefox, ESR, and Thunderbird versions prior to latest patches. Potential for data theft, malware injection, or session hijacking via phishing. Targets include users on older versions, with briefings noting risks in enterprise and consumer sectors.
• Response and Mitigations: Mozilla urges immediate updates to Firefox 141 or ESR equivalents. Enable auto-updates, use extensions like uBlock Origin for phishing protection, and monitor for anomalies via browser logs. No IOCs published, but hunt for unexpected crashes or network calls. CISA may add to KEV if wild exploitation escalates.

These vulnerabilities are frequently featured in daily threat intelligence feeds due to browsers' high attack surface. For detailed PoCs (e.g., from Pwn2Own) or advisory links, check Mozilla's site.