Intel has made available microcode updates for the Ivy Bridge and Sandy Bridge processor families, designed to address Spectre and Meltdown vulnerabilities.
According to Intel's microcode update document (March 6), patches for several processor families have entered production, most notably the second-generation Core (Sandy Bridge) and third-generation Core (Ivy Bridge) families. The patches also cover architectures including the Gladden Xeon of the Sandy Bridge generation, and the Broadwell Xeon chips.
Westmere Xeons, based upon 2010's first-generation Core architecture, as well as Westmere's predecessors, the Nehalem Xeon chips, are also ready to be patched, according to the document. Intel has issued beta patches for these, as well as some of the Arrandale and Clarkdale chips.
Other chip architectures are still waiting for patches, including the remainder of the Arrandale and Clarkdale families.
Soon after the Spectre and Meltdown vulnerabilities were publicly disclosed in early January, Intel began issuing patches for the affected processors, which included the bulk of its products. Unfortunately, those patches were found to cause system instability, forcing Intel to halt and then reissue new code.
Curently no known attacks exploiting either Spectre or Meltdown have occurred.