CVE-2021-27774 is a vulnerability identified in HCL Software's HCL Digital Experience product, specifically affecting versions 8.5, 9.0, and 9.5. The vulnerability is categorized under CWE-209, which pertains to information exposure through error messages. In this case, the issue arises because user input is reflected in error responses generated by the application. This behavior can inadvertently leak sensitive information or provide attackers with clues about the system's internal workings. Although the vulnerability itself does not directly allow unauthorized access or code execution, the exposure of user input in error messages can be leveraged in social engineering or phishing attacks. For example, attackers could craft malicious URLs or inputs that trigger error messages containing their payload, thereby increasing the credibility of phishing attempts by making error responses appear legitimate or tailored. The CVSS v3.1 score assigned to this vulnerability is 3.1, indicating a low severity level. The vector string (AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N) shows that the attack is network-based, requires high attack complexity, no privileges, and user interaction, with no impact on confidentiality or availability but a low impact on integrity. No known exploits are currently reported in the wild, and no official patches are linked in the provided data, suggesting that mitigation may rely on configuration changes or updates from the vendor. Overall, this vulnerability is primarily a concern for the integrity of user interactions and the potential for social engineering rather than direct system compromise.

For European organizations using HCL Digital Experience versions 8.5, 9.0, or 9.5, this vulnerability poses a moderate risk primarily in the context of phishing and social engineering attacks. While the direct technical impact on system confidentiality, integrity, and availability is low, the exposure of user input in error messages can be exploited to craft more convincing phishing campaigns targeting employees or customers. This can lead to credential theft, unauthorized access, or further exploitation through secondary attacks. Organizations in sectors with high reliance on web portals for customer interaction, such as finance, government, healthcare, and e-commerce, may face increased risks if attackers use this vulnerability to enhance the credibility of phishing attempts. Additionally, compliance with GDPR and other European data protection regulations requires minimizing unnecessary data exposure, including in error messages. Failure to address this vulnerability could lead to reputational damage and regulatory scrutiny if exploited in phishing campaigns that result in data breaches or fraud.

To mitigate the risk posed by CVE-2021-27774, European organizations should implement the following specific measures: 1) Review and sanitize all error messages generated by HCL Digital Experience to ensure that user input is not reflected back in responses. This may involve customizing error handling routines or applying vendor-provided patches or updates once available. 2) Implement strict input validation and output encoding to prevent injection of malicious content into error messages. 3) Configure web application firewalls (WAFs) to detect and block suspicious requests that attempt to exploit error message reflection. 4) Educate employees and users about phishing risks, emphasizing awareness of suspicious URLs and error messages that may be crafted to appear legitimate. 5) Monitor logs for unusual error message patterns or repeated triggering of error responses that include user input, which could indicate attempted exploitation. 6) Engage with HCL Software support to obtain any available patches or recommended configuration changes addressing this vulnerability. 7) Conduct regular security assessments and penetration testing focused on error handling and information disclosure to proactively identify and remediate similar issues.