CVE-2026-76447 in Identity Services Engine
Summary
by MITRE • 09/16/2026
A vulnerability in the Online Certificate Status Protocol (OCSP) responder of Cisco ISE and Cisco ISE-PIC could allow an unauthenticated, remote attacker to cause an administrative reload of the OCSP responder certificate and key material.
This vulnerability is due to missing authentication on a function of the OCSP responder. An attacker could exploit this vulnerability by sending a crafted request to an affected device. A successful exploit could allow the attacker to cause the OCSP responder to reload certificate and key material on demand.
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Analysis
by VulDB Data Team • 09/16/2026
The Online Certificate Status Protocol serves as a critical component in public key infrastructure, enabling clients to verify whether digital certificates have been revoked before establishing secure communications. Cisco Identity Services Engine utilizes this protocol to manage authentication policies based on the status of client or server certificates. The vulnerability described involves a fundamental failure in access control within the OCSP responder module of Cisco ISE and its physical interface card variant. Specifically, there is an absence of mandatory authentication for certain administrative functions related to certificate management. This architectural flaw allows any remote entity with network connectivity to interact directly with these sensitive operations without providing valid credentials or passing through standard security checkpoints.
An unauthenticated attacker can exploit this weakness by crafting specific network requests directed at the OCSP responder service running on the affected device. By sending a specially constructed packet that targets the vulnerable function, the attacker triggers an immediate reload of the certificate and key material associated with the OCSP responder. This action effectively forces the system to discard its current cryptographic identity and load new or modified credentials without authorization. The operational impact is severe because it compromises the integrity of the authentication infrastructure. If an attacker can manipulate which certificates are recognized as valid by reloading them on demand, they may be able to bypass certificate-based access controls, impersonate legitimate users, or disrupt service availability depending on how the reload affects ongoing sessions and policy enforcement points.
From a classification perspective, this vulnerability aligns with CWE-287, which denotes Improper Authentication, specifically regarding the failure to verify identity before performing administrative actions. It also relates to CWE-693, Protection Mechanism Failure, as the security controls intended to restrict access to certificate management functions are bypassed entirely. In terms of adversary behavior, this exploitation technique corresponds to ATT&CK tactic T1078, Valid Accounts, although in this case, it is an unauthenticated attack that effectively grants administrative privileges by exploiting a logic flaw rather than stealing existing credentials. The ability to reload key material remotely also touches upon potential impacts related to availability and integrity of cryptographic operations.
Mitigation strategies must focus on restricting network access to the OCSP responder interface immediately if possible. Administrators should ensure that management interfaces are not exposed directly to untrusted networks such as the public internet or general user VLANs without strict firewall rules limiting source IP addresses to known administrative hosts. Additionally, applying vendor-provided patches is essential to resolve the underlying code deficiency where authentication checks were omitted for specific API endpoints or internal functions. Regular auditing of access logs can help detect attempts to interact with these vulnerable endpoints before successful exploitation occurs. Ensuring that certificate management workflows require multi-factor authentication and role-based access control further reduces the risk surface associated with such critical infrastructure components.