Mozilla released Firefox 159 for Windows, Android, macOS, and Linux. The update fixes 167 security bugs. Of these, 108 are rated high severity, and the rest are rated moderate or low. Almost 100 are use-after-free (UAF) vulnerabilities, which ZDNET describes as memory management flaws that an attacker could exploit to crash the browser or trigger malicious code. Several bugs also involve Firefox's Sandbox, which ZDNET says could let hackers break through the protected area to run malicious code.
Google released a Chrome update with 52 security fixes, according to the report. Four are rated critical and 46 are rated high. The four critical bugs point to a memory corruption problem and also reference the Sandbox. ZDNET reports that an attacker exploiting them could bypass Chrome's Sandbox to run malicious code. Several Chrome bugs are also UAF issues.
ZDNET advises users to update both browsers now. In Firefox, users open the menu, select Help and Report, then About Firefox, and restart the browser after the update installs. In Chrome, users open the three-dot menu, select Help, then About Google Chrome, and restart after the download.
Mozilla credited Amy Burnett, a security researcher and analyst at OpenAI, with uncovering many of the Firefox bugs. Google's blog post attributed the discovery of several Chrome flaws to Anthropic's Claude and a few to OpenAI. ZDNET's parent company, Ziff Davis, filed an April 2025 lawsuit against OpenAI alleging copyright infringement in training and operating its AI systems.