External risk intelligence

Cisco License On-Prem API Vulnerability Allows Arbitrary File Writes and DoS

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2026-76454

The vulnerability exists in the management API of Cisco License On-Prem (SSM On-Prem). Management interfaces and centralized licensing/software management portals are commonly deployed as accessible service endpoints within an organization's network infrastructure, and such management APIs are often exposed or reachable as part of their operational design for remote administration or system integration.

Path Traversal

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in Cisco License On-Prem software, specifically within its management API. This issue could allow unauthorized remote attackers to write files to the system or cause a denial of service, impacting the availability and integrity of the affected application.

  • Attackers can write files or disrupt service.
  • It affects critical software management tools.
  • Confirm relevance and verify system exposure.

Attack Path

How an attacker could exploit the issue

An unauthenticated attacker could exploit this vulnerability by sending a specially crafted request to the Cisco License On-Prem management API. This could allow them to write arbitrary files to the system, potentially leading to critical system modifications, or cause a denial-of-service condition, making the application unusable.

  • No authentication required for access.
  • Triggered by sending a crafted API request.
  • Allows arbitrary file writes or denial of service.

Live Threat

Current exploitation, exposure, and threat context

A vulnerability in the Cisco Smart Licensing Utility API could allow an unauthenticated, remote attacker to write arbitrary files to the system or cause a denial-of-service (DoS) condition on an affected application. This could occur when the management API is accessed with a crafted request, potentially leading to unauthorized modification of system files or service disruption.

  • System files could be written.
  • Crafted requests sent to the API.
  • Service disruption or file modification.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability impacts Cisco License On-Prem, formerly SSM On-Prem. Ownership likely falls to the infrastructure or platform teams managing this Cisco software, with initial triage involving the network and security teams to confirm exposure and business criticality. The first practical move is to identify all instances, verify their accessibility, and determine the accountable owner before planning remediation based on risk.

  • Identify asset owners; confirm exposure.
  • Verify critical systems; plan maintenance windows.
  • Coordinate vendor engagement; reduce risk.

Supplementary metadata

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

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Frequently asked questions

What is Cisco License On-Prem?

Cisco License On-Prem, formerly known as Cisco Smart Software Manager On-Prem, is a centralized management platform used by organizations to handle software licenses and entitlements across their internal infrastructure. It provides a dedicated management API designed to facilitate system integration and automated licensing tasks, serving as a critical backend service for maintaining software compliance and operational connectivity for other Cisco products deployed within an environment.

What does CVE-2026-76454 mean for the system?

This vulnerability is classified as CWE-23, which involves path traversal or improper input validation. In the context of this CVE, the lack of authentication and insufficient input checks in the API mean the application does not properly sanitize incoming requests. Consequently, an attacker can manipulate the API to write files to unintended locations on the server or force the application to crash, resulting in a denial-of-service condition.

How is this vulnerability triggered?

An attacker triggers this flaw by sending a specially crafted request directly to the affected management API. Because the API lacks authentication, no prior login or valid user credentials are required to initiate the malicious request. Note that simply browsing the web interface or performing standard, non-malicious administrative tasks does not trigger this vulnerability; it requires the specific, crafted input to manipulate file system operations.

Why should I care about this vulnerability?

You should care because management interfaces like this one are frequently reachable within an organization's network to support remote administration and service integration. According to Halo Surface Signal, these APIs are often designed to be accessible service endpoints, increasing the likelihood that they are reachable by unauthorized parties if they are not properly segmented or restricted by network-level access controls.

How do I respond to this threat?

Start by identifying all instances of Cisco License On-Prem within your environment and verifying their current network accessibility. Engage with the platform or infrastructure teams responsible for these systems to confirm who owns the software. Once identified, evaluate the risk to your business operations and coordinate with your security team to restrict access to the management API while you prepare for vendor-supplied maintenance.

References

Sources and related resources

Primary sources: NVD, CVE.org.

NVDPublished