CVE-2025-49221 is a security vulnerability identified in the Mattermost Confluence Plugin versions prior to 1.5.0. The vulnerability is classified under CWE-862, which pertains to missing authorization. Specifically, the plugin fails to enforce authentication checks for users accessing the Mattermost instance when making API calls to the GET subscription endpoint. This flaw allows unauthenticated attackers to retrieve subscription details without any credentials or user interaction. The vulnerability is network exploitable (AV:N) but requires high attack complexity (AC:H), meaning that an attacker must have a detailed understanding of the plugin's API and possibly the environment to exploit it successfully. No privileges are required (PR:N), and no user interaction is needed (UI:N). The impact is limited to confidentiality (C:L), with no impact on integrity or availability. The vulnerability does not have known exploits in the wild as of the publication date (August 11, 2025). The absence of authentication enforcement means that sensitive subscription information could be exposed, potentially revealing subscription plans, user counts, or billing details, which could be leveraged for further reconnaissance or social engineering attacks. However, the scope is limited to the Mattermost Confluence Plugin, which is an integration component between Mattermost and Atlassian Confluence, used primarily for collaboration and communication within organizations. The CVSS score is 3.7, indicating a low severity level due to limited impact and high complexity of exploitation.

For European organizations using Mattermost with the Confluence Plugin, this vulnerability could lead to unauthorized disclosure of subscription details, which may include sensitive business information such as subscription tiers, user licenses, or billing data. While this does not directly compromise user data or system integrity, the exposure of subscription information could facilitate targeted phishing or social engineering campaigns against employees or IT staff. Additionally, knowledge of subscription details might aid attackers in planning more sophisticated attacks by understanding the scale and scope of the Mattermost deployment. Organizations in regulated sectors such as finance, healthcare, or government might face compliance concerns if subscription data is considered sensitive under data protection regulations. However, since the vulnerability does not allow access to user messages or critical system functions, the direct operational impact is limited. The lack of known exploits reduces immediate risk, but the vulnerability should be addressed promptly to prevent future exploitation.

European organizations should prioritize upgrading the Mattermost Confluence Plugin to version 1.5.0 or later, where the authentication enforcement issue has been resolved. Until the patch is applied, organizations can implement network-level access controls to restrict API endpoint exposure, such as firewall rules limiting access to trusted IP ranges or VPN-only access. Monitoring API access logs for unusual or unauthenticated requests to the GET subscription endpoint can help detect potential exploitation attempts. Additionally, organizations should review and tighten Mattermost instance permissions and audit plugin configurations to ensure minimal exposure. Employing Web Application Firewalls (WAFs) with custom rules to block unauthenticated API calls to sensitive endpoints can provide an additional layer of defense. Finally, educating IT and security teams about this vulnerability will help maintain vigilance and ensure timely response to any suspicious activity.