CVE-2025-9826 is a stored cross-site scripting (XSS) vulnerability identified in M-Files Corporation's Hubshare product, affecting versions prior to 25.8. This vulnerability arises from improper neutralization of input during web page generation (CWE-79), allowing authenticated attackers to inject malicious scripts that are stored and subsequently executed in the context of other users' browsers. The vulnerability requires the attacker to have some level of authentication (low privilege), but does not require user interaction beyond the victim viewing the affected content. The CVSS 4.0 score is 7.0 (high severity), reflecting the network attack vector, low attack complexity, no privileges required for the attacker beyond authentication, and partial user interaction. The vulnerability impacts confidentiality and integrity primarily by enabling script execution that could lead to session hijacking, credential theft, or unauthorized actions performed on behalf of the victim user. Availability impact is low. No known exploits are currently reported in the wild, and no patches or mitigation links are provided yet. The vulnerability is significant because Hubshare is a collaboration and document sharing platform used by enterprises, meaning that exploitation could compromise sensitive business data and user accounts.

For European organizations using M-Files Hubshare, this vulnerability poses a significant risk to the confidentiality and integrity of sensitive corporate data and user credentials. Attackers exploiting this flaw could execute arbitrary scripts in the browsers of authenticated users, potentially leading to session hijacking, unauthorized data access, or manipulation of shared documents. Given the collaborative nature of Hubshare, this could facilitate lateral movement within organizations or data leakage. The requirement for attacker authentication limits exposure somewhat, but insider threats or compromised accounts could be leveraged. The impact is particularly critical for sectors with stringent data protection requirements under GDPR, as exploitation could result in data breaches with regulatory and reputational consequences. Additionally, the partial user interaction requirement means that users must view malicious content, which could be embedded in shared documents or messages, increasing the risk of inadvertent exploitation.

European organizations should prioritize upgrading M-Files Hubshare to version 25.8 or later once available, as this will contain the official fix. Until patches are released, organizations should implement strict input validation and output encoding on all user-generated content within Hubshare to prevent script injection. Employing Content Security Policy (CSP) headers can help mitigate the impact of XSS by restricting script execution sources. Organizations should also enforce strong authentication controls and monitor for unusual account activity to detect potential misuse of compromised credentials. User awareness training should emphasize caution when interacting with shared content, especially from less trusted sources. Network segmentation and limiting Hubshare access to trusted internal networks can reduce exposure. Finally, logging and monitoring for anomalous behaviors related to Hubshare usage can aid in early detection of exploitation attempts.