CVE-2026-4147 is a vulnerability classified under CWE-457 (Use of Uninitialized Variable) affecting MongoDB Server versions 7.0, 8.0, and 8.2. The flaw arises from the improper handling of stack memory during the execution of the filemd5 command, which calculates the MD5 hash of files stored in the database. An authenticated user with the read role can issue specially crafted filemd5 commands that cause the server to return limited portions of uninitialized stack memory. This memory leakage can potentially expose sensitive data residing in stack variables, which may include cryptographic keys, internal pointers, or other confidential information. The vulnerability requires no user interaction and no elevated privileges beyond read access, making it relatively easy to exploit by insiders or attackers who have obtained read credentials. The CVSS 4.0 base score is 7.1 (high), reflecting the network attack vector, low attack complexity, no privileges required beyond read, and high confidentiality impact. Integrity and availability are not impacted. No patches were linked at the time of disclosure, and no known exploits have been reported in the wild. However, the presence of uninitialized memory disclosure can facilitate further attacks such as privilege escalation or data exfiltration. MongoDB Server is widely deployed in enterprise, cloud, and web application environments, making this vulnerability relevant to a broad range of organizations worldwide.

The primary impact of CVE-2026-4147 is unauthorized disclosure of sensitive information through leakage of uninitialized stack memory. This can compromise confidentiality by exposing internal server data that might include cryptographic material or application secrets. Attackers with read access can leverage this information to escalate privileges, bypass security controls, or conduct targeted attacks against the affected systems. Since the vulnerability requires only read role authentication, any compromised or insider account with read permissions is sufficient to exploit it. This broadens the attack surface, especially in environments with multiple users or third-party integrations. Although integrity and availability are not directly affected, the confidentiality breach can lead to significant downstream risks, including data breaches and regulatory non-compliance. Organizations relying heavily on MongoDB for critical data storage, especially in sectors like finance, healthcare, and government, face increased risk. The lack of known exploits currently reduces immediate threat but does not eliminate the potential for future weaponization.

1. Monitor MongoDB usage logs for unusual or excessive filemd5 command invocations, especially from users with read roles. 2. Restrict read role assignments strictly to trusted and necessary users; implement the principle of least privilege. 3. Apply vendor patches promptly once they become available to address the uninitialized memory handling in the filemd5 command. 4. Consider implementing network segmentation and access controls to limit exposure of MongoDB instances to only authorized systems and users. 5. Use encryption at rest and in transit to reduce the impact of any leaked data. 6. Conduct regular audits of user permissions and review authentication mechanisms to detect and prevent unauthorized access. 7. Employ runtime application self-protection (RASP) or database activity monitoring tools that can detect anomalous command usage patterns. 8. If patching is delayed, consider disabling or restricting the filemd5 command usage via MongoDB configuration or role-based access control where feasible.