G1

March 05, 2026

Added CSCwt41941 in the Open Caveats section in the release 4.3(6.260003).

H0

February 23, 2026

Created release notes for 4.3(6.260017) for the following servers:

• Cisco UCS C220 M8, C225 M8, C240 M8 and C245 M8 servers

• Cisco UCS C220 M7 and C240 M7 servers

• Cisco UCS C220 M6, C240 M6, C225 M6 and C245 M6 servers

• Cisco UCS S3260 M5 servers

The firmware files in Cisco Host Upgrade Utility for individual releases are available at: Cisco UCS C-Series Integrated Management Controller Firmware Files, Release 4.3

G0

January 14, 2026

Created release notes for 4.3(6.260003) for the following servers:

• Cisco UCS C220 M8 and C240 M8 servers

• Cisco UCS C220 M7 and C240 M7 servers

The firmware files in Cisco Host Upgrade Utility for individual releases are available at: Cisco UCS C-Series Integrated Management Controller Firmware Files, Release 4.3

C1

December 10, 2025

Added CSCws30219 in the Open Caveats section in the release 4.3(6.250053).

F0

November 13, 2025

Created release notes for 4.3(6.250117) for the following servers:

• Cisco UCS C220 M7 servers

The firmware files in Cisco Host Upgrade Utility for individual releases are available at: Cisco UCS C-Series Integrated Management Controller Firmware Files, Release 4.3

E0

October 28, 2025

Created release notes for 4.3(6.250101) for the following servers:

• Cisco UCS C220 M8, C225 M8, C240 M8 and C245 M8 servers

• Cisco UCS C220 M7 and C240 M7 servers

• Cisco UCS C220 M6, C240 M6, C225 M6 and C245 M6 servers

• Cisco UCS S3260 M5 servers

The firmware files in Cisco Host Upgrade Utility for individual releases are available at: Cisco UCS C-Series Integrated Management Controller Firmware Files, Release 4.3

D0

August 25, 2025

Created release notes for 4.3(6.250060) for the following servers:

• Cisco UCS C245 M8 servers

The firmware files in Cisco Host Upgrade Utility for individual releases are available at: Cisco UCS C-Series Integrated Management Controller Firmware Files, Release 4.3

C0

July 7, 2025

Created release notes for 4.3(6.250053) for the following servers:

• Cisco UCS C220 M8, C225 M8, C240 M8 and C245 M8 servers

• Cisco UCS C220 M7 and C240 M7 servers

• Cisco UCS C220 M6, C240 M6, C225 M6 and C245 M6 servers

• Cisco UCS S3260 M5 servers

The firmware files in Cisco Host Upgrade Utility for individual releases are available at: Cisco UCS C-Series Integrated Management Controller Firmware Files, Release 4.3

B0

May 22, 2025

Created release notes for 4.3(6.250044) for the following servers:

• Cisco UCS C220 M8, C225 M8, C240 M8 and C245 M8 servers

• Cisco UCS C220 M7 and C240 M7 servers

The firmware files in Cisco Host Upgrade Utility for individual releases are available at: Cisco UCS C-Series Integrated Management Controller Firmware Files, Release 4.3

A0

April 30, 2025

Created release notes for 4.3(6.250039) for the following servers:

• Cisco UCS C220 M8, C240 M8 servers

• Cisco UCS S3260 M5 servers

The firmware files in Cisco Host Upgrade Utility for individual releases are available at: Cisco UCS C-Series Integrated Management Controller Firmware Files, Release 4.3

Created release notes for 4.3(6.250040) for the following servers:

• Cisco UCS C225 M8 and C245 M8 servers

• Cisco UCS C220 M7 and C240 M7 servers

• Cisco UCS C220 M6, C240 M6, C225 M6 and C245 M6 servers

The firmware files in Cisco Host Upgrade Utility for individual releases are available at: Cisco UCS C-Series Integrated Management Controller Firmware Files, Release 4.3

Version 134.0.6998.89 (Official Build) (64-bit)

Version 133.0.6943.141 (Official Build) (64-bit)

Version 133.0.6943.127 (Official Build) (arm64)

Mac OS 15.3.1

CSCwr46765

When setting up Cisco UCS C-Series servers, if the BMC time has not yet synchronized with the BIOS and the RAID controller's certificate has a newer date, then Cisco IMC may display the following error on the RAID controller:

Description: Storage controller MRAID inoperable: reseat or replace the storage controller MRAID

Severity: critical

Cause: equipment-inoperable

Description: Unauthorized card detected, replace the adapter

However, this is expected behavior because the RAID cannot authenticate as the BMC time is still earlier than the device certificate date. And this results in SPDM Authentication Failure.

4.3(6.250040)

4.3(6.260003)

CSCwr64033

After performing a Reset to Factory Defaults (RFD) on a Cisco UCS C-series M8 server, it is not possible to access the Cisco IMC using the default credentials.

When attempting the initial CIMC configuration using the [F8] menu, the following error appears:

Current CIMC password does not match.

This error may also occur on a previously working server immediately after an RFD (Reset to Factory Defaults) operation.

4.3(6.250053)

4.3(6.260003)

CSCws30219

Cisco UCS M7 servers are susceptible to host lockups triggered by ECC (Error Correcting Code) memory events.

This issue is specifically related to how the server’s BIOS interacts with the EFI (Extensible Firmware Interface) during error conditions. During these events, the BIOS does not correctly retrieve a required variable, causing EFI to return an invalid parameter. As a result, the operating system is unable to continue normal operation and freezes without logging any errors. When this occurs, the host becomes unresponsive and KVM (keyboard, video, mouse) input is not accepted.

Single-bit ECC errors—while not logged due to DDR5 specifications—can trigger this condition, resulting in complete loss of host responsiveness.

4.3(6.250053)

4.3(6.260003)

CSCwr75284

On Cisco UCS C220 M7 servers with Intel processors, enabling immersion cooling mode may trigger frequent soft PSOC faults, which causes the host power state to become locked.

When this happens, you cannot change the server’s power state from either the web interface or the IMM. This behavior does not occur when the servers use standard air cooling.

To avoid this problem in immersion cooling mode, the system has been updated, so that soft PSOC faults no longer lock the host power.

4.3(6.250053)

4.3(6.250117)

CSCwq61388

On Cisco UCS C220 M6 servers running firmware version 4.3.5 or later, enabling VMD in BIOS with multiple NVME drives can cause storage subsystem initialization to exceed 15 minutes, leading to Intersight Server Profile deployment failures. Disabling VMD or reducing the number of drives can resolve the issue. Earlier firmware versions may not be affected.

.

4.3(5.250001)

4.3(6.250101)

CSCwq74490

On Cisco UCS C245 M8 platform with AMD EPYC 9655 processors, fully loaded NVIDIA L4 GPUs occasionally experience PCIe link width downgrades on random slots when running the Linux Rebooter Stress test. This can cause GPUs to operate at reduced speeds in the OS environment.

4.3(6.250053)

4.3(6.250060)

CSCwo79652

Cisco IMC CLI might not show the command:

In addition, Cisco IMC CLI might not display the details for Admin Link Training and Oper Link Training.

4.3(6.250039)

4.3(6.250040)

CSCwo67388

In Cisco UCS C220 M8 and C240 M8 servers operating in Standalone or IMM mode, Cisco IMC does not verify the new password against the previously used passwords.

The number of previously used passwords that are saved in Cisco IMC depends on the latest value configured in the Password History setting.

You can configure this setting any number of times to any valid value between 1 to 5.

4.3(6.250012)

4.3(6.250053)

CSCwm45755

M.2 SATA disks connected to storage controllers on the MSTOR-RAID slot are not being detected during the installation of Windows Server 2025.

The affected storage controllers are:

• UCS-M2-HWRAID2 on Cisco UCS C220/C240 M8 Servers

• UCSC-M2RM-M8 on Cisco UCS C220/C240 M8 Servers

• UCSC-M2RR-240M8 on Cisco UCS C240 M8 Servers

This issue is specific to Windows Server 2025 for the storage controllers mentioned above.

These M.2 disks, however, are detected and fully functional in Windows Server 2022 or other operating systems.

4.3(6.250039)

4.3(6.250044)

CSCwn22341

HSU Redfish API update fails for Cisco UCS VIC 15xxx adapters with "ApplyTime":"OnNextBoot" option and when the target contains only VIC adapters.

This issue is now resolved.

4.3.5.240021

4.3(6.250039)

4.3(6.250040)

CSCwn48372

In Cisco UCS M8 servers, setting the BIOS token to "Auto" for CbsCmnEfficiency

ModeEnRs results in the value being displayed as High Performance Mode.

This issue is now resolved.

4.3.5.240021

4.3(6.250039)

4.3(6.250040)

CSCwt41941

In Cisco UCS M8 servers, the system may become stuck in the KVM console and fail to boot, accompanied by BIOS attestation failure messages. POST processes might hang or not complete, and CATERR events can be logged. NVME devices may become inoperable, and temperature sensor failures along with critical thermal threshold errors can occur.

These issues arise when downgrading firmware from the following release versions to earlier releases that use SSP 1.6.

• 4.3(6.260003)

• 6.0(1.250192)

The above release versions are integrated with SSP Protocol Version 2.0.

The SSP Protocol Version 2.0 introduced in these later releases is not backward compatible with SSP 1.6, causing the BMC to fail BIOS attestation and resulting in system stability and hardware errors.

1. Upgrade only the BMC firmware component to the latest version using the Host Server Utility (HSU) or the Cisco IMC interface.

2. Perform a host reset.

   Performing a host reset may help recover the state, but it is not guaranteed to be 100% effective.

The supported latest release versions include:

• 4.3(6.260003)

• 6.0(1.250192)

The above release versions are integrated with SSP Protocol Version 2.0.

Avoid downgrading from these versions to earlier releases that do not support SSP Protocol Version 2.0.

• 4.3(6.260003)

• 6.0(1.250192)

CSCws30219

Cisco UCS M7 servers are susceptible to host lockups triggered by ECC (Error Correcting Code) memory events.

This issue is specifically related to how the server BIOS interacts with the EFI (Extensible Firmware Interface) during error conditions.

During these events, the BIOS does not correctly retrieve a required variable, causing EFI to return an invalid parameter.

As a result, the operating system is unable to continue normal operation and freezes without logging any errors. When this occurs, the host becomes unresponsive and KVM (keyboard, video, mouse) input is not accepted.

Single-bit ECC errors—while not logged due to DDR5 specifications—can trigger this condition, resulting in complete loss of host responsiveness.

Downgrade to version 4.3(6.250044) or an earlier release.

4.3(6.250053)

CSCwo52218

When a Cisco UCS S3260 M5 server has undergone a NIC mode change since the chassis's last power-on, its management IP address may become unreachable following an AC power cycle or a reboot of the Active CMC (Chassis Management Controller).

The gateway is set to 0.0.0.0 after AC power cycle or reboot of active CMC.

There is no workaround.

3.1(3a)

CSCwo60509

In Cisco UCS C240 M8 servers, if the controller is attached in NoRaid system and U.3 NVMe drives are to be used under the controller, then either perform Backplane Reset to Default or manually change backplane management to controller-attached

If NoRaid system needs to be inserted with the Storage card and U.3 NVMe drives are to be used under the controller, then either perform Backplane reset to factory default or manually change the Backplane Management slot personality to Controller-attached.

4.3(6.250039)

CSCwn95239

In Cisco UCS servers, the server does not get powered on due to BIOS corruption.

The following message is displayed:

Power on failure asserted [Power on Fail, Server failed to power-on]

This issue might occur when the BIOS flashing is interrupted due to CMOS clear operation triggered during update or Factory default, Cisco IMC reboot or any other operation.

• Reboot Cisco IMC.

• Activate backup BIOS.

• Update BIOS and activate it.

4.3(6.250039)

4.3(6.250040)

CSCwn47257

The VIC firmware is displayed with G at the end.

For example: 5.3(5.32)-48G.

Flash the same image and perform the power-cycle of the host.

4.3(6.250039)

4.3(6.250040)

CSCwo67280

In Cisco UCS servers with the Cisco IMC release version 4.3.5.250001, the VIC OOB firmware update is not triggered in the CLI for the activate command.

Use other user interfaces to activate the VIC firmware.

In the CLI, use the no-activate command to trigger and perform the power-cycle of the host manually.

4.3(6.250039)

4.3(6.250040)

CSCwm33093

Virtual disk is displayed as Inoperable state when the disks are in online state.

Drive assignments to the span are firmware driven to optimize the performance.

Due to this, user-provided span details is over-ridden by firmware.

For the span inventory, use the arcconf output to know the exact drive assignments in the spans.

Whatever is configured in the span assignment using the management tools will not be honoured because the firmware overrides with its own assignment to optimize the performance.

4.3.5.250030

CSCwo79652

Cisco IMC CLI might not show the command:

set admin-link-training

In addition, Cisco IMC CLI might not display the details for Admin Link Training and Oper Link Training.

Use the Cisco IMC GUI to configure Admin Link Training or to view the details of Admin Link Training and Oper Link Training.

4.3(6.250039)

4.3(6.250040)

CSCwn44614

When Pre-Boot DMA Protection is enabled on Cisco UCS C220 M8 servers, you may experience slowness while downloading the OS ISO image via HTTP/HTTPS boot. This issue occurs during the pre-boot process when attempting HTTP/HTTPS boot with this configuration.

Disable Pre Boot DMA Protection BIOS Policy token

4.3(6.250039)

CSCwn51498

Raw OEM SEL records are logged in CIMC SEL during the booting and shutdown of Windows Server 2025 on Cisco UCS C220 M8 servers.

Ignore the Raw OEM SEL records logged while booting Windows 2025.

4.3(6.250039)

CSCwn99720

On Cisco UCS C-Series M8 servers with Intel processors and an R1S CPU configured in a single CPU setup on the 2S platform, Intel SGX remains disabled even after being enabled in the BIOS.

This issue does not occur with a dual CPU configuration.

There is no known workaround.

4.3(6.250039)

CSCwm45755

M.2 SATA disks connected to storage controllers on the MSTOR-RAID slot are not being detected during the installation of Windows Server 2025.

The affected storage controllers are:

• UCS-M2-HWRAID2 on Cisco UCS C220/C240 M8 Servers

• UCSC-M2RM-M8 on Cisco UCS C220/C240 M8 Servers

• UCSC-M2RR-240M8 on Cisco UCS C240 M8 Servers

This issue is specific to Windows Server 2025 for the storage controllers mentioned above.

These M.2 disks, however, are detected and fully functional in Windows Server 2022 or other operating systems.

There is no known workaround.

4.3(6.250039)

CSCwr10524

In Cisco UCS M6 servers with firmware release version 4.3(2.230207) and secure VIC 15xxx adapters, the firmware upgrade to the release versions 4.3(4.xxxxx) / 4.3(5.xxxxx) / 4.3(6.xxxxx) / 6.0(1.250127) using the HUU Web UI or NI-HUU results in BIOS activation failure.

The issue occurs if any one or both of the following secure VICs are present:

• Cisco UCS VIC 15235

• Cisco UCS VIC 15425

If the update is initiated through the HUU GUI, then the interface first displays a failure message regarding secure VIC activation, followed by another message to proceed with a host power cycle.

After a manual host power cycle, all the component firmware are activated with the latest firmware except for BIOS. Retriggering firmware update does not help in activating the BIOS component.

If the update is initiated through NI-HUU, then the script execution fails with the following error message:

Error - Firmware update failed because it timed out. Check host for details.

After a manual host power cycle, all the component firmware are activated with the latest firmware except for BIOS. Retriggering firmware update does not help in activating the BIOS component.

You can perform any one of the following workarounds:

Perform the firmware upgrade using the HSU Redfish.

OR

Perform a step upgrade as listed below:

1. Upgrade from the release version 4.3(2.230207) to 4.3(2.230270)

2. Upgrade from the release version 4.3(2.230270) to any of the following releases -

   • 4.3(4.xxxxx)

   • 4.3(5.xxxxx)

   • 4.3(6.xxxxx)

   • 6.0(1.xxxxx)

OR

Perform the following steps in Cisco IMC Web UI:

1. From the Apps drop-down list, select Administration.

2. In the Navigation pane, click Firmware Management menu.

3. In the Firmware Management area, select a component from the Component column and click Upload.

4. The Update Firmware dialog box appears.

5. Update the secure VIC 15xxx firmware.

6. Update the remaining components by booting HUU.

4.3(4.240152)