Cisco Nexus 1000V Series Switches Virtual Ethernet Modules contain an issue that could allow Ethernet traffic to bypass the Cisco Virtual Security Gateway. Updates are not available.
Cisco Nexus 1000V Series Switches Virtual Ethernet Modules (VEM) contain an issue that could allow traffic to bypass the Cisco Virtual Security Gateway (VSG).
The issue is due to a bug when handling VSG licenses during an in-service upgrade of the affected software to Software Release 4.2(1)SV1(5.2) from Software Release 4.2(1)SV1(5.1a) or prior. The bug can result in a state in which the VEM is in unlicensed mode for VSG even when the device is configured with permanent VSG licenses and the Virtual Supervisor Module (VSM) continues to show it as licensed. As a result of the unlicensed mode for VSG, all the virtual Ethernet ports on the VEM of the affected device may stay in No-Policy pass-through mode; virtual machines (VM) are not firewalled and traffic is not passed through the VSG.
An unauthenticated, remote attacker could exploit this issue by attempting to convince an administrator to initiate a valid in-service software upgrade to Software Release 4.2(1)SV1(5.2). A successful exploit could allow the attacker to bypass the VSG and may be used by the attacker as a precursor to future attacks.
Cisco has confirmed this issue in a Cisco Security Response; however software updates are not yet available.
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical
Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at email@example.com.
An unauthenticated, remote attacker could exploit this issue to bypass the VSG, which the attacker may use as a precursor to future attacks.
Administrators are advised to contact the vendor regarding the future availability of Software Release 4.2(1)SV1(5.2a).
Administrators are advised to restrict access to affected systems.
Administrators are advised to monitor critical systems.
Administrators are advised to review the workaround procedures detailed in the Cisco Security Response.
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