Apple and Samsung have vowed to quickly fix any vulnerabilities in their products following WikiLeaks' disclosure of an alleged CIA hacking arsenal capable of breaking into iPhones and other devices.
The archive claims to show the CIA exploiting weaknesses it discovers in hardware and software systems - without informing manufacturers of the flaws in question.
"While our initial analysis indicates that many of the issues leaked today were already patched in the latest iOS, we will continue work to rapidly address any identified vulnerabilities," Apple said in a statement.
"We always urge customers to download the latest iOS to make sure they have the most recent security updates."
Samsung offered a similar response.
"Protecting consumers' privacy and the security of our devices is a top priority at Samsung," a statement from the South Korean electronics giant said.
"We are aware of the report in question and are urgently looking into the matter."
WikiLeaks claims the documents it released on Tuesday are part of a vast trove of leaked CIA documents, tools and code representing "the majority of its hacking arsenal".
The CIA would neither confirm nor deny the documents were genuine.
However, "the American public should be deeply troubled by any WikiLeaks disclosure designed to damage the Intelligence Community's ability to protect America against terrorists and other adversaries," a CIA spokesman said in a statement.
"Such disclosures not only jeopardise US personnel and operations, but also equip our adversaries with tools and information to do us harm."
According to the documents, the CIA has produced more than 1,000 malware systems - viruses, trojans, and other software - that can infiltrate and take control of target electronics.
US intelligence and law enforcement officials said on Wednesday they have been aware since the end of last year of a security breach at the CIA and were focusing on contractors as the likeliest source of documents being passed on to WikiLeaks.
The officials, who spoke on condition of anonymity, told Reuters news agency they believed the documents were authentic.
The White House said on Wednesday that President Donald Trump was "extremely concerned" about a CIA security breach.
"Anybody who leaks classified information will be held to the highest degree of law," spokesman Sean Spicer told reporters.
One official with knowledge of the investigation said companies that are contractors for the CIA have been checking to see which of their employees had access to the material that WikiLeaks published.
In Germany on Wednesday, the chief federal prosecutor's office said it would review the WikiLeaks documents because some suggested the CIA ran a hacking hub from the US consulate in Frankfurt.
"We're looking at it very carefully," said a spokesman for the federal prosecutor's office. "We will initiate an investigation if we see evidence of concrete criminal acts or specific perpetrators."
Source: News agencies