CVE-2023-37517 is a vulnerability identified in HCL Software's HCL Domino Leap product, specifically affecting versions 1.0 through 1.0.5 and 1.1 through 1.1.1. The issue stems from the absence of appropriate "no-cache" HTTP headers in responses generated by the application. This omission allows sensitive information to be stored in client-side caches, such as browser caches or intermediary proxy caches, potentially exposing confidential data to unauthorized parties who gain access to the cached content. The vulnerability is classified under CWE-524, which concerns the use of caches containing sensitive information. Technically, when sensitive data is transmitted without cache-control headers like "Cache-Control: no-store" or "Pragma: no-cache", browsers and proxies may retain this data beyond the intended session scope. This can lead to data leakage if other users share the same device or if the device is compromised. The CVSS 3.1 base score is 3.2, indicating a low severity level. The vector string (AV:L/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N) shows that the attack requires local access (AV:L), low complexity (AC:L), low privileges (PR:L), and user interaction (UI:R). The scope is changed (S:C), meaning the vulnerability affects resources beyond the initially vulnerable component. The impact on confidentiality is low, with no impact on integrity or availability. No known exploits are currently reported in the wild, and no patches have been linked yet. This vulnerability primarily risks unauthorized disclosure of sensitive cached data rather than direct system compromise or denial of service.

For European organizations using HCL Domino Leap, this vulnerability could lead to inadvertent exposure of sensitive information through cached data on client devices or intermediary caches. This is particularly concerning in environments where devices are shared or not adequately secured, such as in public or semi-public workspaces. The confidentiality impact, while rated low, can still result in leakage of business-critical or personal data, potentially violating data protection regulations like the GDPR. Since the vulnerability requires local access and user interaction, remote exploitation is unlikely without prior access. However, insider threats or compromised endpoints could exploit this to harvest cached sensitive information. The lack of impact on integrity and availability means operational disruption or data tampering is not a concern here. Nevertheless, the exposure of sensitive data could damage organizational reputation and lead to compliance issues, especially in sectors handling personal or financial data. Organizations with high compliance requirements or those operating in regulated industries should consider this vulnerability a risk to their data confidentiality posture.

To mitigate this vulnerability, organizations should implement the following specific measures: 1) Apply any forthcoming patches or updates from HCL Software as soon as they become available to ensure proper cache-control headers are set. 2) As an immediate workaround, configure web server or reverse proxy rules to inject appropriate cache-control headers (e.g., "Cache-Control: no-store, no-cache, must-revalidate" and "Pragma: no-cache") for responses from HCL Domino Leap endpoints serving sensitive data. 3) Educate users on the risks of caching sensitive information and encourage practices such as clearing browser caches regularly, especially on shared or public devices. 4) Enforce endpoint security policies that restrict local access to authorized personnel only and implement session timeouts or automatic cache clearing mechanisms on client devices. 5) Monitor network traffic and logs for unusual access patterns that might indicate attempts to access cached sensitive data. 6) Review and tighten access controls around HCL Domino Leap deployments to minimize the risk of local attackers gaining the necessary access to exploit this vulnerability. These steps go beyond generic advice by focusing on immediate technical controls and user behavior adjustments tailored to the nature of this caching issue.