Mozilla has successfully addressed a critical bug related to Firefox that caused the web browser to crash on desktop systems powered by Intel’s Raptor Lake CPUs. With the latest stable release of Firefox version 151.01, the company has managed to patch the issue that has been under investigation for more than a year.
Mozilla engineers initially zeroed in on failures in a zlib-rs compression routine where certain dist values appeared incorrect, resulting in index out-of-bounds crashes. However, the root cause was tied to Intel’s Raptor Lake CPU instructions, specifically RPL050 and RPL060, which sometimes caused the CPU cores to read incorrect or outdated data.
Senior Staff Engineer Gabriele Svelto first flagged the issue last year, blaming Intel for its CPU instabilities and highlighting mass browser crash reports coming from systems powered by Intel Raptor Lake, specifically in locations suffering from heat waves.
“If you have an Intel Raptor Lake system and you’re in the northern hemisphere, chances are that your machine is crashing more often because of the summer heat. I know because I can literally see which EU countries have been affected by heat waves by looking at the locales of Firefox crash reports coming from Raptor Lake systems,” said Svelto on Mastodon.
He also noted that while Intel’s newer 0x12c microcode update significantly reduced the number of crashes, the bugs came back with the release of version 0x12F.
Intel’s Raptor Lake CPU instability issues first began surfacing in late 2022 before exploding the following year with users reporting widespread game crashes, browser instability, and system failures on 13th-gen and 14th-gen processors. Intel eventually confirmed after several months that the root cause was tied to a physical degradation issue caused by prolonged exposure to excessive voltage and heat. While the company rolled out several microcode patches, including 0x125, 0x129, 0x12B, and, more recently, 0x12F, these updates were only designed to mitigate the conditions triggering the degradation rather than reverse existing damage. Eventually, Intel announced an extended warranty for customers facing the issue from three to five years.
If you have been facing Firefox crashes on your desktop PC running Intel’s 13th-gen or 14th-gen Raptor Lake CPUs, it is recommended to update the browser to its latest stable version by heading to the official page here.
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