Most of the claims against Huawei are fabricated, as you’d expect when spies are involved on both sides. But a Bloomberg article by Jordan Robertson and Jamie Tarabay has enough intriguing details to suggest at least a plausible claim.

A decade ago, a software update from Huawei contained malicious code that worked much like a digital wiretap, reprogramming the infected equipment to record all the communications passing through it before sending the data to China.

It only worked for a few days and then self-destructed. That’s consistent with a spy agency testing an exploit.

The careful reporting, based on 7 sources within allied security agencies, concluded

China’s spy services were behind the breach, having infiltrated the ranks of Huawei technicians who helped maintain the equipment and pushed the update to the telecom’s systems. … American intelligence agencies that year confirmed a similar attack from China using Huawei equipment located in the U.S.,

Bloomberg

From which I infer that Huawei’s corporate management did not approve the action. The Bloomberg headline, Chinese Spies Accused of Using Huawei in Secret Australia Telecom Hack, suggests the same conclusion.

Huawei’s leadership has repeatedly said they have not and will not cooperate with Chinese spying. Ren and others have almost certainly lived up to that; the $100 billion Five Eyes security apparatus would have found evidence.

Cisco was similarly involved in espionage, apparently inadvertently.

Routers built for export by Cisco (and probably other companies) are routinely intercepted without Cisco’s knowledge by the National Security Agency and equipped with hidden surveillance tools.

https://www.infoworld.com/article/2608141/snowden–the-nsa-planted-backdoors-in-cisco-products.html based on Snowdon leaks

John Suffolk, Huawei’s global cybersecurity officer, told the reporters, “no tangible evidence has ever been produced of any intentional wrongdoing of any kind.”

Bloomberg noted that

The NSA had already penetrated Huawei’s corporate networks in China, looking for evidence of any links between the company and China’s military, according to documents leaked by former NSA contractor Edward Snowden and published in news articles in 2014. Under a program called Shotgiant, the U.S. monitored e-mail accounts belonging to Huawei employees including Ren, the company’s founder. NSA also looked for ways to exploit Huawei products in Chinese-built networks in countries considered high-priority intelligence targets, including Afghanistan, Cuba, Iran, Kenya and Pakistan, according to the documents and articles. 

https://www.spiegel.de/international/world/nsa-spied-on-chinese-government-and-networking-firm-huawei-a-960199.html

We live in a world with spies, few if any as ubiquitous as the United States