These reviews — carried out under the banner of making elections more secure, and misleadingly labeled audits to lend an air of official sanction — have given rise to their own new set of threats to the integrity of the voting machines, software and other equipment that make up the nation’s election infrastructure.

Election officials and security experts say the reviews have created problems ranging from the expensive inconvenience of replacing equipment or software whose security has been compromised to what they describe as a graver risk: that previously unknown technical vulnerabilities could be discovered by partisan malefactors and exploited in future elections.

In Arizona, election officials have moved to replace voting machines in the state’s largest county, Maricopa, after conservative political operatives and other unaccredited people gained extensive access to them as they conducted a widely criticized review of the 2020 results. In Pennsylvania, the secretary of state decertified voting equipment in rural Fulton County after officials there allowed a private company to participate in a similar review.