Apple Addresses Meltdown and Spectre in macOS Sierra and OS X El Capitan With New Security Update
Along with macOS High Sierra 10.13.3, Apple this morning released two new security updates that are designed to address the Meltdown and Spectre vulnerabilities on machines that continue to run macOS Sierra and OS X El Capitan.
As outlined in Apple's security support document, Security Update 2018-001 available for macOS Sierra 10.12.6 and OS X El Capitan 10.11.6 offers several mitigations for both Meltdown and Spectre, along with fixes for other security issues, and the updates should be installed immediately.

Apple addressed the Meltdown and Spectre vulnerabilities in macOS High Sierra with the release of macOS High Sierra 10.13.2, but older machines were left unprotected. Apple initially said a prior security update included fixes for the two older operating systems, but that information was later retracted.
Spectre and Meltdown are two hardware-based vulnerabilities that impact nearly all modern processors. Apple in early January confirmed that all of its Mac and iOS devices were impacted, but Meltdown mitigations were introduced ahead of when the vulnerabilities came to light in iOS 11.2 and macOS 10.13.2, and Spectre was addressed through Safari updates in iOS 11.2.2 and a macOS 10.13.2 Supplemental Update.
Spectre and Meltdown take advantage of the speculative execution mechanism of a CPU. As these use hardware-based flaws, operating system manufacturers are required to implement software workarounds. These software workarounds can impact processor performance, but according to Apple, the Meltdown fix has no measurable performance reduction across several benchmarks.
The Spectre Safari mitigations have "no measurable impact" on Speedometer and ARES-6 tests, and an impact of less than 2.5% on the JetStream benchmark.
Many PCs with Intel processors have been facing serious issues following the installation of patches with fixes for Meltdown and Spectre, but these problems do not appear to impact Apple's machines.
Popular Stories
Apple is looking for a "breakthrough" with its push into wearable AI devices, including an "AirTag-sized pendant," according to Bloomberg's Mark Gurman.
In a report this week, he said the pendant is reminiscent of the failed Humane AI Pin, but it would be an iPhone accessory rather than a standalone product.
The pendant would feature an "always-on" camera and a microphone for Siri voice...
Apple today announced a "special Apple Experience" in New York, London, and Shanghai, taking place on March 4, 2026 at 9:00am ET.
Apple invited select members of the media to the event in three major cities around the world. It is simply described as a "special Apple Experience," and there is no further information about what it may entail. The invitation features a 3D Apple logo design...
New trade-in data indicates that Apple's iPhone 17 Pro Max has rapidly become the single most traded-in smartphone.
According to a new report from SellCell, Apple's latest flagship iPhone has quickly risen to the top of the independent trade-in market, accounting for 11.5% of all devices appearing in the top-20 trade-in rankings just months after release. The analysis is based on SellCell...
Back at WWDC 2025, Apple revealed that it was planning to allow CarPlay users to watch video via AirPlay in their vehicles while they are not driving, and the first beta of iOS 26.4 suggests the feature may be nearing availability.
There are several new references to CarPlay video streaming functionality within the iOS 26.4 beta's source code. The feature is not yet visible to users, but...
Apple will announce its rumored low-cost MacBook at its event on March 4, with the device coming in a selection of bold color options, according to a known leaker.
Earlier this week, Apple announced a "special Apple Experience" for the media in New York, London, and Shanghai, taking place on March 4, 2026 at 9:00am ET.
Posting on Weibo, the leaker known as "Instant Digital" said that the...