CVE-2025-58576 is a Cross-Site Request Forgery (CSRF) vulnerability identified in multiple editions of the GroupSession collaboration software developed by Japan Total System Co., Ltd. The affected versions include GroupSession Free edition prior to 5.3.0, GroupSession byCloud prior to 5.3.3, and GroupSession ZION prior to 5.3.2. CSRF vulnerabilities allow attackers to trick authenticated users into submitting unauthorized requests to the vulnerable application by exploiting the user's active session. In this case, if a logged-in user visits a malicious webpage controlled by an attacker, the attacker can cause the user's browser to send crafted requests to GroupSession, resulting in unintended operations being performed without the user's consent. The vulnerability has a CVSS 3.0 base score of 4.3, indicating medium severity. The vector string (AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N) shows that the attack can be performed remotely over the network with low attack complexity, requires no privileges, but does require user interaction. The impact is limited to integrity loss, with no confidentiality or availability impact. No known exploits have been reported in the wild as of the publication date, December 12, 2025. The vulnerability was assigned by JPCERT and is publicly disclosed. Since GroupSession is a collaboration platform, unauthorized operations could include modifying data or settings, potentially disrupting workflows or causing data inconsistencies. The lack of patches linked in the report suggests that users should monitor vendor advisories closely for updates. Mitigation typically involves implementing anti-CSRF tokens, validating HTTP headers, and educating users to avoid clicking suspicious links while logged in.

For European organizations using GroupSession products, this vulnerability poses a risk of unauthorized actions being performed within their collaboration environment if users are tricked into visiting malicious websites. While it does not compromise data confidentiality or system availability, the integrity of data and operations can be affected, potentially leading to workflow disruptions, unauthorized changes to shared documents or settings, and loss of trust in the collaboration platform. Organizations with remote or hybrid workforces are particularly vulnerable due to increased exposure to phishing and social engineering attacks. The medium severity rating reflects the limited scope of impact but acknowledges the ease of exploitation via user interaction. If exploited at scale, it could lead to operational inefficiencies and require incident response efforts. The absence of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits following public disclosure. European entities relying on GroupSession for critical collaboration should consider this vulnerability a priority for remediation to maintain operational integrity.

1. Apply vendor patches promptly once they are released for GroupSession Free edition (≥5.3.0), byCloud (≥5.3.3), and ZION (≥5.3.2). 2. In the interim, implement web application firewall (WAF) rules to detect and block suspicious cross-site requests targeting GroupSession endpoints. 3. Enable and enforce anti-CSRF tokens in all forms and state-changing requests within the application if configurable. 4. Restrict the use of HTTP methods that can cause state changes (e.g., POST, PUT) to trusted origins only via CORS policies. 5. Educate users about the risks of clicking unknown or suspicious links while logged into GroupSession, emphasizing phishing awareness. 6. Monitor user activity logs for unusual or unauthorized operations that could indicate exploitation attempts. 7. Consider isolating GroupSession access to trusted networks or VPNs to reduce exposure. 8. Regularly review and update session management policies to minimize session lifetime and reduce risk from stolen sessions.