Cisco UCS Central CVE-2026-76506: management-plane RCE
Cisco fixes CVE-2026-76506 in UCS Central. An authenticated attacker can run commands, write files and obtain sensitive information.
- AUTHOR
- Karol Rapacz / CEO Breachroad · OSCP · PNPT
- PUBLISHED
- 5 November 2026
- READING TIME
- 9 min read
- TOPIC
- Vulnerabilities and CVEs
Cisco has disclosed CVE-2026-76506 in UCS Central Software, a web management interface vulnerability that allows an authenticated remote attacker to execute commands, write arbitrary files and obtain sensitive information from the device. The flaw has a CVSS 3.1 score of 7.6 and affects the product regardless of configuration.
The attack requires valid credentials but no interaction from another user. In a system that manages data-centre infrastructure, a low-privileged account does not automatically mean low risk: the bug can turn a compromised operator account into access to the appliance operating system and management-plane data.
The priority action: update UCS Central 2.1 to release 2.1(2c). Releases 2.0 and earlier must migrate to a fixed version. Cisco provides no workaround, so restricting the interface and reviewing accounts are valuable interim controls but do not replace the update.
What Cisco published on November 4
Cisco published the advisory on November 4, 2026. The vulnerability exists in the UCS Central web-based management interface and results from insufficient validation of user-supplied input in an HTTP request.
An attacker with a valid account can send a crafted request to an affected endpoint. Successful exploitation can allow the attacker to:
- execute arbitrary commands on the appliance;
- write arbitrary files to the filesystem;
- obtain sensitive information;
- affect the integrity and availability of the management system.
The CVSS vector is AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L: a low-complexity network attack requiring low privileges and no further user interaction. Confidentiality carries the highest assessed impact.
Cisco PSIRT is not aware of public announcements or malicious use of this CVE. This is not a confirmed zero-day attack; it is a newly disclosed vulnerability with a fix available.
Why UCS Central is a sensitive target
UCS Central provides centralised management for multiple Cisco UCS domains. The control plane holds information about infrastructure, policy, configuration and administrative identities. Compromise of such a system carries a different weight from compromise of one application server.
Command execution and arbitrary file writes may enable persistence, configuration changes or further movement through the management network. Sensitive-information disclosure may reveal hostnames, topology, integration data and secrets useful in later attack stages.
It would still be inaccurate to claim automatically that the CVE gives direct control of every physical server. The actual blast radius depends on architecture, assigned privileges, integrations and the data and credentials available to UCS Central. Each organisation must determine that scope in its own environment.
Affected versions
| Deployed line | Required action |
|---|---|
| UCS Central 2.0 and earlier | migrate to a fixed release |
| UCS Central 2.1 | update to 2.1(2c) |
Cisco says the vulnerability affects UCS Central regardless of device configuration. An organisation should not consider the system safe because a particular feature is disabled.
Before deployment, confirm that hardware, memory and integrations remain supported by the target release. Migrating from an older branch requires a separate plan, configuration backup and recovery test.
Remediation plan for organisations
1. Find every instance
Review production, standby, lab and post-migration systems. Verify the software version running on each instance rather than relying only on a CMDB or procurement record.
2. Restrict the management interface
The interface should be reachable only from a dedicated administrative network or controlled jump host. Remove exposure to the internet and broad user segments. Require MFA where the authentication architecture supports it.
3. Review accounts before and after the change
Remove former employee and contractor accounts, disable shared logins and reduce roles. Review last-use dates and failed attempts. A valid account is a prerequisite for exploitation, so identity hygiene directly reduces the attack opportunity.
4. Update or migrate
Install at least 2.1(2c) on the 2.1 line. Migrate older releases to a fixed version using Cisco documentation and support. Preserve the configuration and prepare a rollback plan.
5. Hunt for evidence
Review HTTP requests to the interface, unusual sign-ins, file creation and modification, process execution, configuration changes and outbound connections. Correlate local records with firewall, proxy and identity-provider logs because an attacker with command execution may affect evidence held on the appliance.
Response when exploitation is suspected
Preserve logs, configuration and available system images first. Do not begin by deleting one suspicious file, which could destroy evidence without establishing the full scope.
Isolate the management system in line with continuity plans, block suspicious accounts and identify exposed secrets and integrations. Rotate credentials, tokens and keys that may have been readable. Review UCS domains, identity systems and administrator workstations for follow-on activity.
After rebuilding from a trusted source, install the fixed release and enable off-box logging. A control-plane incident needs broader scoping than reinstalling the console alone.
Link the response to risk-based vulnerability management so management systems rank above ordinary hosts with a similar CVSS score.
Source facts and Breachroad conclusions
Cisco confirms an authenticated network attack, command execution, arbitrary file writes, information disclosure, the absence of a workaround and the 2.1(2c) fix. The vendor is not aware of public exploitation or announcements.
Prioritisation based on control-plane role, review of integration secrets, correlation with external logs and extending the investigation to UCS domains are Breachroad conclusions based on the possible impact. Administrators can rehearse escalation and post-compromise decisions through cybersecurity training for organisations. An IT security audit can assess interface exposure and segmentation.
FAQ: Cisco CVE-2026-76506
Does exploitation require authentication?
Yes. Cisco says the attacker must have valid credentials on the affected device. The CVSS vector assumes low privileges.
Is there a workaround without updating?
No. Cisco provides no workaround that addresses the vulnerability. Interface restrictions are important but remain interim controls.
Is every UCS Central configuration affected?
Yes. Cisco says the product is affected regardless of device configuration. The installed software release determines whether the system is fixed.
Is the flaw already exploited?
Cisco PSIRT is not aware of public announcements or malicious use. Organisations therefore have an opportunity to patch before confirmed widespread attacks.
Primary sources: Cisco — CVE-2026-76506 Security Advisory, Cisco — Security Advisories RSS.
