Computers and other devices using a common networking protocol may be vulnerable to attack.
The warning came yesterday from Cert Co-ordination Centre, a computer security organisation based at Carnegie Mellon University and backed by the United States Department of Defence.
Cert issued an advisory this week warning that the earliest version of Simple Network Management Protocol (SNMP) - used in many software programs, Internet routers and even consumer electronics such as digital cameras - had vulnerabilities that 'may allow unauthorised privileged access, denial-of-service attacks, or cause unstable behaviour'.
The protocol allows devices to be managed remotely.
Cert said the latest version was not affected by the security flaw, though the early version was common enough for the flaw to be of concern.
Cert's advisory included responses from about 50 vendors, including 3Com, Cisco, Microsoft, Compaq, Marconi and Red Hat.
Most advised turning off the SNMP functions until patches were released. Some said patches for their products were available or in the works.