Cisco IOS XR Software Enhanced Preboot eXecution Environment Unsigned Code Execution Vulnerability

A vulnerability in the enhanced Preboot eXecution Environment (PXE) boot loader for Cisco IOS XR 64-bit Software could allow an unauthenticated, remote attacker to execute unsigned code during the PXE boot process on an affected device. The PXE boot loader is part of the BIOS and runs over the management interface of hardware platforms that are running Cisco IOS XR Software only.

The vulnerability exists because internal commands that are issued when the PXE network boot process is loading a software image are not properly verified. An attacker could exploit this vulnerability by compromising the PXE boot server and replacing a valid software image with a malicious one. Alternatively, the attacker could impersonate the PXE boot server and send a PXE boot reply with a malicious file. A successful exploit could allow the attacker to execute unsigned code on the affected device.

Note: To fix this vulnerability, both the Cisco IOS XR Software and the BIOS must be upgraded. The BIOS code is included in Cisco IOS XR Software but might require additional installation steps. For further information, see the Fixed Software section of this advisory.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:

Security Impact Rating: High

CVE: CVE-2020-3284


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How to Upgrade the LOM Firmware on Any NetScaler MPX Platform

This article describes how to upgrade the Lights Out Management (LOM) firmware for NetScaler appliances. The appliance list includes all MPX models with NetScaler firmware 10.5 GA build 64,11.0 GA build 69 or newer, and 11.1 GA build 49 or newer.


NetScaler MPX hardware


This procedure requires two reboots to complete and therefore a disruption in production traffic is expected. Hence it is recommended that the procedure be carried out during a maintenance window on the secondary node of a NetScaler HA pair to minimize disruption to production traffic.


ADC | GUI Access lost after firmware upgrade

in a lot of environments, due to the COVID situation there was spike in access to VPN based services, and in some situations slowness was observed in loading VPN / AAA Login page, to mitigate this problem some changes were done on httpd.conf file (

With a customized httpd.conf (for the above or any other reason), GUI issues can occur, an excerpt from the article below.

WARNING – Following the above solution might result in issues with future firmware upgrades.

When you apply the above configuration, the httpd.conf will not be updated during a future firmware upgrade. This could cause the GUI to become completely unavailable.

If this occurs, you must delete the file /nsconfig/httpd.conf (on both primary and then secondary node), reboot the ADC, and then reapply the below settings.

The clear diagnosis of that issue is that if you run “ps aux | grep httpd” in shell mode, there will be no httpd processes running.


SDX went into hung state with the error message “rejecting I/O to offline device”



Single Bundle Image (SBI) upgrade to 12.1-53.12 will upgrade the Platform and will move the LSI Firmware to the latest 23.34.0-0019. This latest LSI Firmware version ( 23.34.0-0019) has a fix for the SDX hung issue. Thus, install 12.1 build 53.12 using Single Bundle Upgrade Image again and ensure if the LSI Firmware version has upgraded to 23.34.0-0019.

After the Single Bundle upgrade, you can verify the LSI firmware either from the XenServer console using the below command or by collecting the support bundle of XenServer of SDX appliance.

/opt/MegaRAID/MegaCli/MegaCli -AdpAllinfo -aAll