CVE-2026-108015 in Notes Client
Summary
by MITRE • 10/27/2026
Private keys for eight eMudhra intermediate CA certificates have been compromised https://emudhra.we-have-a-problem.com/ , which impacts certificate trust for outbound network request features of HCL Notes Client. An unauthenticated network attacker could spoof server certificates to execute a man in the middle (MITM) attack, enabling them to intercept and/or modify the content of outbound TLS connections.
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Analysis
by VulDB Data Team • 10/27/2026
The compromise of private keys associated with eight intermediate Certificate Authority certificates issued by eMudhra represents a critical failure in public key infrastructure security that directly undermines the trust model relied upon by HCL Notes Client for securing outbound network communications. In standard Transport Layer Security implementations, clients validate server identities by verifying digital signatures against trusted root and intermediate CA certificates stored within their local certificate stores. When an attacker gains control of the private keys corresponding to these specific intermediates, they can cryptographically sign fraudulent X.509 certificates that appear valid to any client trusting those authorities. This effectively nullifies the authentication guarantees provided by TLS, allowing a malicious actor to impersonate legitimate servers without triggering standard certificate validation errors in HCL Notes Client configurations that include eMudhra as a trusted authority.
From an operational perspective, this vulnerability enables unauthenticated network attackers positioned within the communication path between the client and remote services to execute sophisticated man-in-the-middle attacks. By intercepting outbound TLS connections initiated by the HCL Notes Client, an attacker can present a spoofed certificate signed with one of the compromised eMudhra private keys. Since the client will successfully validate this fraudulent certificate against its trusted store, it establishes an encrypted session believing it is communicating securely with the intended destination. In reality, all data transmitted over this connection is decrypted by the attacker before being re-encrypted and forwarded to the actual server or vice versa. This capability allows for the complete interception of sensitive information such as login credentials, proprietary documents, email content, and other confidential business intelligence exchanged through HCL Notes applications.
The technical flaw lies in the lifecycle management and revocation processes surrounding these intermediate CA certificates rather than a weakness in the cryptographic algorithms themselves. The exposure suggests potential vulnerabilities in key generation environments, secure storage mechanisms, or access controls within eMudhra’s infrastructure that allowed unauthorized extraction of private material. Furthermore, it highlights the risk inherent in relying on third-party Certificate Authorities where a single compromise can cascade across thousands of dependent clients and services globally. For HCL Notes users, this means that any outbound connection to servers presenting certificates issued by these specific intermediates is potentially compromised unless additional verification mechanisms are employed. The impact extends beyond simple data eavesdropping; attackers could also modify traffic in transit, injecting malicious code or altering transactional data while maintaining the appearance of a secure and unmodified communication channel.
Mitigation strategies must address both immediate remediation and long-term architectural resilience. Organizations utilizing HCL Notes Client should immediately audit their certificate stores to identify if eMudhra intermediate certificates are present as trusted authorities. If possible, administrators should remove these specific intermediates from the trust store or configure strict pinning policies that validate against known public keys rather than relying solely on CA hierarchy validation for critical internal services. It is imperative to monitor official advisories from both HCL and eMudhra for updates regarding certificate revocation lists and new trusted anchors. Clients must ensure their systems are configured to check Certificate Revocation Lists or Online Certificate Status Protocol responses, although reliance on these mechanisms alone may be insufficient if the CA itself has been compromised at a deep level.
This incident aligns with Common Weakness Enumeration categories such as CWE-327 regarding the use of broken cryptographic algorithms and CWE-519 concerning access to sensitive information due to missing or incorrect access control, specifically within the context of key management failures. In terms of adversary tactics, this scenario maps directly to MITM techniques described in the MITRE ATT&CK framework under Tactic TA0040: Privilege Escalation and more specifically related to network sniffing and credential harvesting via interception. The ability to spoof certificates is a foundational enabler for subsequent attacks including session hijacking and data exfiltration, making this a high-severity vulnerability that requires immediate attention from security operations teams managing HCL Notes environments.