CVE-2026-22881 is a cross-site scripting vulnerability identified in the Message function of Cybozu Garoon versions 5.15.0 to 6.0.3. This vulnerability allows an attacker to inject malicious scripts into the messaging component, which can be triggered when a user interacts with crafted messages. The exploitation requires the attacker to have some level of privileges (PR:L) and user interaction (UI:R), such as clicking a malicious link or viewing a crafted message. The vulnerability does not impact confidentiality directly but compromises integrity by enabling attackers to reset arbitrary users’ passwords, effectively allowing account takeover. The attack vector is network-based (AV:N), with low attack complexity (AC:L), and the scope remains unchanged (S:U). The vulnerability leverages the XSS flaw to manipulate the password reset mechanism, potentially bypassing authentication controls. Although no public exploits are known yet, the presence of this vulnerability in widely used versions of Cybozu Garoon, a popular enterprise collaboration platform, poses a significant risk. The vendor has not yet published patches, so organizations must implement interim mitigations. The vulnerability’s CVSS 3.0 base score is 5.7, reflecting medium severity due to the combination of attack complexity, required privileges, and user interaction.

For European organizations, this vulnerability poses a risk of unauthorized password resets leading to account takeovers within Cybozu Garoon environments. Such compromises could allow attackers to impersonate legitimate users, access sensitive corporate communications, manipulate scheduling, or disrupt collaboration workflows. The integrity of user accounts is at risk, which may cascade into broader organizational impacts if privileged accounts are compromised. While confidentiality and availability impacts are limited, the ability to reset passwords without proper authorization undermines trust in the platform’s security. Organizations in sectors relying heavily on Cybozu Garoon for internal communication—such as finance, government, and technology—may face operational disruptions and potential data integrity issues. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits once patches are released. European GDPR regulations also impose obligations to protect user data and account integrity, making timely mitigation critical to avoid compliance issues.

1. Monitor Cybozu, Inc. official channels closely for security patches addressing CVE-2026-22881 and apply them promptly upon release. 2. Implement strict input validation and output encoding on the Message function to prevent injection of malicious scripts, if possible via configuration or custom controls. 3. Enforce Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts within the application context. 4. Limit the privileges of users who can send messages or interact with the messaging function to reduce the attack surface. 5. Educate users to be cautious about interacting with unexpected or suspicious messages, especially those containing links or scripts. 6. Monitor logs and alerts for unusual password reset activities or multiple reset attempts to detect potential exploitation attempts early. 7. Consider deploying Web Application Firewalls (WAF) with custom rules to detect and block XSS payloads targeting the messaging component. 8. Review and strengthen authentication and password reset workflows to add additional verification steps, such as multi-factor authentication (MFA), to mitigate the impact of unauthorized resets.