According to TechRepublic, a critical memory corruption vulnerability in Firefox exposed approximately 180 million users to potential code execution attacks for six months before being discovered. The WebAssembly bug, tracked as CVE-2025-13016, was uncovered by AISLE’s autonomous AI system during a security deep dive. The flaw involved subtle pointer arithmetic mistakes in Firefox’s WebAssembly garbage collection implementation that could corrupt memory and potentially allow arbitrary code execution. Mozilla moved quickly to deploy fixes in Firefox 145 and ESR 140.5+ after being notified. The vulnerability specifically affected the StableWasmArrayObjectElements class where mismatched pointer types caused incorrect copying of inline array data. Attackers could exploit this through carefully crafted WebAssembly modules that manipulated array-to-string conversion processes.
Why this matters
Here’s the thing about browser security – we’re talking about the most critical piece of software on most people’s devices. When a bug like this slips through for six months, it shows just how complex modern browsers have become. WebAssembly was supposed to be this safe, sandboxed environment for running code at near-native speeds. But this vulnerability basically punched holes in those safety assumptions. And we’re not talking about some obscure edge case – this affected the core garbage collection system that handles memory management. That’s like finding a structural flaw in the foundation of a building that’s already occupied.
The exploitation game
What’s particularly clever about this vulnerability is how specific the conditions needed to be for exploitation. Attackers had to deliberately force Firefox into memory pressure situations to trigger the garbage collection fallback path. They’d craft specific array sizes, manipulate memory usage, and repeatedly trigger array-to-string conversions. It’s like knowing exactly which buttons to push to make the system fail in a predictable way. The fact that it required this level of precision is probably why it stayed hidden for so long. But once discovered? Security researchers could reliably reproduce the memory corruption and direct it toward chosen targets on the stack. That’s the scary part – this wasn’t some random crash bug, it was weaponizable.
Broader implications
This incident really highlights the arms race in browser security. Mozilla, Google, Apple – they’re all building these incredibly complex platforms with multiple layers of protection. But as AISLE’s research shows, even the most rigorously engineered systems can have subtle flaws. The fact that AI systems are now finding vulnerabilities that human researchers missed is both encouraging and concerning. It suggests we’re reaching levels of complexity where traditional security auditing might not be enough. Meanwhile, organizations relying on web technologies for critical operations need to understand that browser security isn’t just about patching – it’s about defense in depth, monitoring, and containment strategies.
What you should do
If you’re responsible for any Firefox deployments, the immediate priority is getting everyone updated to Firefox 145 or later. Enterprise environments should verify version compliance across all systems – don’t assume automatic updates have worked. For high-security environments where immediate patching isn’t possible, consider temporarily disabling WebAssembly entirely. But here’s the reality: completely disabling modern web features often isn’t practical for business operations. That’s where layered security comes in. Monitor for WebAssembly-related memory errors in your EDR systems. Use network-level defenses to block suspicious content. And consider browser isolation for high-risk browsing activities. The CVE-2025-13016 details make it clear this was a serious vulnerability, but the broader lesson is that browser security requires continuous vigilance, not just emergency patching.
