CVE-2026-26335 is a vulnerability identified in Calero VeraSMART versions prior to 2022 R1, stemming from the use of hard-coded cryptographic keys in the ASP.NET machineKey configuration within the web.config file. The machineKey is critical for securing ASP.NET ViewState data by providing integrity and optionally encryption. In this case, static keys stored in a predictable location (C:\Program Files (x86)\Veramark\VeraSMART\WebRoot\web.config) allow an attacker who gains access to these keys to craft malicious ViewState payloads. These payloads can bypass integrity validation checks, enabling server-side deserialization attacks that lead to remote code execution (RCE) within the IIS application context. The vulnerability does not require any authentication or user interaction, making it remotely exploitable over the network. The CVSS 4.0 score of 9.3 reflects the critical nature of this flaw, with high impact on confidentiality, integrity, and availability. The vulnerability is classified under CWE-321 (Use of Hard-coded Cryptographic Key), which is a known anti-pattern that weakens cryptographic protections. No public exploits are currently reported, but the technical details suggest that exploitation is straightforward for attackers with access to the keys. The root cause is the static configuration of machineKey values rather than dynamic or per-installation keys, which would prevent reuse of keys across deployments and reduce attack surface. This vulnerability highlights the importance of secure key management and proper cryptographic practices in web applications, especially those handling sensitive data or critical business functions.

The impact of CVE-2026-26335 on European organizations can be severe. Successful exploitation results in remote code execution on the IIS server hosting the VeraSMART application, potentially allowing attackers to fully compromise the affected system. This can lead to unauthorized access to sensitive data, disruption of business operations, and lateral movement within the network. Given VeraSMART's role in enterprise environments, including telecom expense management and IT asset management, attackers could manipulate billing data, disrupt service management, or exfiltrate confidential corporate information. The vulnerability’s ease of exploitation without authentication increases the risk of widespread attacks. European organizations with regulatory obligations under GDPR face additional risks of non-compliance and penalties if data breaches occur. Furthermore, critical infrastructure or government entities using VeraSMART may face national security implications. The lack of known exploits in the wild currently provides a window for proactive mitigation, but the high severity score demands urgent attention to prevent potential targeted attacks.

To mitigate CVE-2026-26335, organizations should immediately upgrade Calero VeraSMART to version 2022 R1 or later, where this vulnerability is addressed. If upgrading is not immediately feasible, administrators should manually replace the hard-coded machineKey values with dynamically generated keys unique to each installation, ensuring they are not stored in publicly accessible or predictable locations. Implementing strict access controls on the web.config file and the server environment reduces the risk of key disclosure. Additionally, enabling ASP.NET ViewState MAC validation with a secure, unique key and considering disabling ViewState if not required can reduce attack surface. Network segmentation to isolate the VeraSMART server and deploying Web Application Firewalls (WAFs) with rules to detect anomalous ViewState payloads can provide additional layers of defense. Continuous monitoring for unusual IIS process behaviors or unexpected deserialization attempts is recommended. Finally, organizations should conduct regular security audits and penetration tests focusing on web application security and cryptographic configurations.