Cisco patches Vulnerability-related.PatchVulnerability a severe flaw in switch deployment software that can be attacked with crafted messages sent to a port that 's open by default . Cisco has released Vulnerability-related.PatchVulnerability patches for 34 vulnerabilities mostly affecting Vulnerability-related.DiscoverVulnerability its IOS and IOS XE networking software , including three critical remote code execution security bugs . Perhaps the most serious issue Cisco has released Vulnerability-related.PatchVulnerability a patch for is critical bug CVE-2018-0171 affecting Vulnerability-related.DiscoverVulnerability Smart Install , a Cisco client for quickly deploying new switches for Cisco IOS Software and Cisco IOS XE Software . A remote unauthenticated attacker can exploit a flaw in the client to reload an affected device and cause a denial of service or execute arbitrary code . Embedi , the security firm that found Vulnerability-related.DiscoverVulnerability the flaw , initially believed it could only be exploited Vulnerability-related.DiscoverVulnerability within an enterprise 's network . However , it found Vulnerability-related.DiscoverVulnerability millions of affected devices exposed on the internet . `` Because in a securely configured network , Smart Install technology participants should not be accessible through the internet . But scanning the internet has shown that this is not true , '' wrote Embedi . `` During a short scan of the internet , we detected 250,000 vulnerable devices and 8.5 million devices that have a vulnerable port open . '' Smart Install is supported by a broad range of Cisco routers and switches . The high number of devices with an open port is probably because the Smart Install client 's port TCP 4786 is open by default . This situation is overlooked by network admins , Embedi said . The company has also published Vulnerability-related.DiscoverVulnerability proof-of-concept exploit code , so it probably will be urgent for admins to patch Vulnerability-related.PatchVulnerability . An attacker can exploit the bug by sending Attack.Phishing a crafted Smart Install message to these devices on TCP port 4786 , according to Cisco . Embedi discovered Vulnerability-related.DiscoverVulnerability the flaw last year , landing it an award at the GeekPwn conference in Hong Kong last May , and reported Vulnerability-related.DiscoverVulnerability it to Cisco in September . Cisco 's internal testing also turned up Vulnerability-related.DiscoverVulnerability a critical issue in its IOS XE software , CVE-2018-0150 , due to an undocumented user account that has a default username and password . Cisco warns Vulnerability-related.DiscoverVulnerability that an attacker could use this account to remotely connect to a device running the software . Cisco engineers also found Vulnerability-related.DiscoverVulnerability CVE-2018-0151 , a remote code execution bug in the QoS subsystem of IOS and IOS XE . `` The vulnerability is due to incorrect bounds checking of certain values in packets that are destined for UDP port 18999 of an affected device . An attacker could exploit this vulnerability by sending malicious packets to an affected device , '' writes Cisco . All three bugs were given a CVSS score of 9.8 out of 10 .