CVE-2025-28104 is a critical security vulnerability classified under CWE-284 (Improper Access Control) affecting laskBlog version 2.6.1. The flaw allows an unauthenticated attacker to bypass access control mechanisms and retrieve all usernames stored within the application by submitting crafted input. This vulnerability is remotely exploitable over the network without requiring any privileges or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The vulnerability impacts confidentiality and integrity, as unauthorized disclosure of usernames can facilitate further attacks such as brute force, credential stuffing, or social engineering. Although availability is not affected, the exposure of sensitive user information poses a significant risk. The vulnerability has a CVSS 3.1 base score of 9.1, reflecting its critical severity. No patches or fixes are currently linked, and there are no known exploits in the wild at the time of publication. The vulnerability was reserved in March 2025 and published in April 2025, suggesting it is a recent discovery. The lack of vendor or product details beyond the application name and version limits the scope of direct attribution but confirms the issue is specific to laskBlog v2.6.1. Given the nature of the vulnerability, attackers can automate username enumeration attacks, potentially leading to broader compromise if combined with other vulnerabilities or weak password policies.

For European organizations using laskBlog v2.6.1, this vulnerability presents a critical risk to user data confidentiality. Exposure of all usernames can facilitate targeted attacks such as phishing, credential stuffing, or brute force password attempts, increasing the likelihood of account compromise. Organizations handling sensitive or personal data may face regulatory consequences under GDPR due to inadequate protection of user information. The integrity of user authentication processes is undermined, potentially leading to unauthorized access if attackers leverage the disclosed usernames. Although availability is not directly impacted, the reputational damage and operational disruptions from subsequent attacks could be significant. The vulnerability's ease of exploitation and lack of required authentication mean that any publicly accessible instance of laskBlog v2.6.1 is at immediate risk. European entities relying on this blogging platform for internal or external communications should consider the threat severe and prioritize remediation to prevent data breaches and compliance violations.

1. Immediate mitigation involves restricting public access to the affected laskBlog v2.6.1 instances, ideally by implementing network-level controls such as IP whitelisting or VPN access to limit exposure. 2. Monitor web server logs for unusual or repeated requests that may indicate username enumeration attempts. 3. If possible, disable or remove the vulnerable functionality until a vendor patch or official fix is released. 4. Implement strong password policies and multi-factor authentication (MFA) to reduce the risk of account compromise even if usernames are exposed. 5. Conduct regular security assessments and penetration tests focusing on access control mechanisms within the application. 6. Engage with the laskBlog vendor or community to obtain or develop patches addressing the vulnerability. 7. Educate users about phishing risks and encourage vigilance against suspicious communications that may leverage disclosed usernames. 8. Prepare incident response plans to quickly address any potential breaches resulting from exploitation of this vulnerability.