Cavium, a maker of semiconductors acquired in 2018 by Marvell, was allegedly identified in documents leaked in 2013 by Edward Snowden as a vendor of semiconductors backdoored for US intelligence. Marvell denies it or Cavium placed backdoors in products at the behest of the US government.
The allegations surfaced in the PhD thesis of Dr Jacob Appelbaum, "Communication in a world of pervasive surveillance: Sources and methods: Counter-strategies against pervasive surveillance architecture." Appelbaum's thesis was published in March 2022 and received little public attention until mentioned in security blog Electrospaces.net last week.
Appelbaum in 2012 worked as an investigative journalist and technical expert with documentarian Laura Poitras on the Snowden leak. He left the Tor Project in 2016 amid disputed allegations and subsequently enrolled in Eindhoven University of Technology in the Netherlands, where he is a postdoctoral researcher in computer science and cryptography.
The thesis, on page 71, footnote 21 says, "While working on documents in the Snowden archive the thesis author learned that an American fabless semiconductor CPU vendor named Cavium is listed as a successful SIGINT 'enabled' CPU vendor. By chance this was the same CPU present in the thesis author’s internet router (UniFi USG3). The entire Snowden archive should be open for academic researchers to better understand more of the history of such behavior."