It is unclear whether the same sort of safety mechanism exists on printers from other vendors, he added.
Stolfo said that Cui and he discovered the LaserJet vulnerability when doing research on vulnerabilities in single-purpose embedded devices such as printers, routers, VoIP phones and digital thermostats. The two researchers plan to release a formal paper describing their findings after HP has had a chance to mitigate the issue, he said.
HP did not immediately respond to a request for comment. In its statement, HP said it is working on a firmware update for the issue. However, it downplayed the threat.
"The specific vulnerability exists for some HP LaserJet devices if placed on a public internet without a firewall," the company said. "In a private network, some printers may be vulnerable if a malicious effort is made to modify the firmware of the device by a trusted party on the network."
LaserJet printers in some Linux or Mac environments could be compromised by someone sending the device a corrupt print job, the company said.
"Speculation regarding potential for devices to catch fire due to a firmware change is false," HP noted. A hardware element known as a thermal breaker prevents LaserJet printers from overheating or causing a fire. "It cannot be overcome by a firmware change or this proposed vulnerability," HP said.
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