Bloomberg reported that Vodafone, Europe's biggest mobile phone company, identified hidden so-called backdoors in software that could have handed Huawei unauthorized access to the carrier's fixed-line network in Italy used to connect to the internet.
The financial news wire cited Vodafone's security briefing documents from 2009 and 2011.
Vodafone told Bloomberg that the issues were resolved, while responding to the report, Huawei said in a statement: "We were made aware of historical vulnerabilities in 2011 and 2012 and they were addressed at the time. Software vulnerabilities are an industry-wide challenge."
Huawei added that it has "a well established public notification and patching process, and when a vulnerability is identified we work closely with our partners to take the appropriate corrective action".
Huawei is facing pushback in some Western markets over fears Beijing could spy on communications and gain access to critical infrastructure if allowed to develop foreign 5G networks offering instantaneous mobile data transfer.
The United States is adamantly opposed to Huawei's involvement because of the firm's obligation under Chinese law to help its home government gather intelligence or provide other security services when required.
British Foreign Secretary Jeremy Hunt has meanwhile urged caution over the role of China's Huawei in the UK, saying the government should think carefully before opening its doors to the technology giant to develop next-generation mobile networks.
His comments Monday came after media reports said Prime Minister Theresa May had conditionally allowed Huawei to build the UK 5G network.