Overview

On December 19, 2025, MongoDB Inc. disclosed a critical new vulnerability, CVE-2025-14847, which has since been dubbed MongoBleed. This vulnerability is a high-severity unauthenticated memory leak affecting MongoDB, one of the world's most popular document-oriented databases. While initially identified as a data exposure flaw, the severity is underscored by the fact that it allows attackers to bypass authentication entirely to extract sensitive information directly from server memory. On December 26, 2025, public proof-of-concept (PoC) exploit code was published and on December 29th, 2025 exploitation in-the-wild has been confirmed.

While CVE-2025-14847 is rated as a high-severity vulnerability, CVSS 8.7, its impact is critical. Successful exploitation allows a remote, unauthenticated attacker to "bleed" uninitialized heap memory from the database server by manipulating Zlib-compressed network packets. This memory often contains high-value secrets such as cleartext credentials, authentication tokens, and sensitive customer data from other concurrent sessions. Because the vulnerability returns "uninitialized heap memory," an attacker cannot target specific credentials or data records with precision; they must instead rely on repeated exploitation attempts and chance to capture sensitive information.

The vulnerability specifically affects MongoDB servers configured to use the Zlib compression algorithm for network messages, which is a common configuration in many production environments. It affects a wide range of versions, including the 4.4, 5.0, 6.0, 7.0, and 8.0 branches. Older, End-of-Life (EOL) versions are also believed to be vulnerable but will not receive official patches, leaving users of legacy systems at significant continued risk.

As of this writing, the public PoC has been successfully verified by Rapid7 Labs. Unlike scenarios where valid exploits are initially scarce, the exploit for MongoBleed is functional and reliable.

Organizations running self-managed MongoDB instances are urged to remediate this vulnerability on an urgent basis, outside of normal patch cycles. Given the nature of the leak, simply patching is insufficient; organizations are advised to also rotate all database and application credentials that may have been exposed prior to remediation.

Mitigation guidance

CVE-2025-14847 affects a wide range of versions, including the 4.4, 5.0, 6.0, 7.0, and 8.0 branches. Older, End-of-Life (EOL) versions are also believed to be vulnerable but will not receive official patches, leaving users of legacy systems at significant continued risk. Organizations managing their own MongoDB instances should prioritize upgrading to the fixed versions released by the vendor (e.g., 8.0.4, 7.0.16, 6.0.20, etc.) immediately. This is the only complete remediation for the vulnerability. 

If an immediate upgrade is not feasible, or if the organization is running an End-of-Life (EOL) version that will not receive a patch, the risk can be effectively mitigated by disabling the Zlib network compressor in the server configuration. This prevents the specific memory allocation path used by the exploit.

In addition, because CVE-2025-14847 allows for the exfiltration of credentials and session tokens from server memory, patching alone is insufficient to ensure security. Administrators should assume that any secrets residing in the database memory prior to patching may have been compromised; therefore, all database passwords, API keys, and application secrets should be rotated immediately after the vulnerability is remediated. 

Rapid7 customers

Exposure Command, InsightVM, and Nexpose

Exposure Command, InsightVM, and Nexpose customers can assess exposure to CVE-2025-14847 with a vulnerability check expected to be available in today's (Dec 29) content release.

Intelligence Hub

Customers leveraging Rapid7’s Intelligence Hub can track the latest developments surrounding CVE-2025-14847, including a Suricata rule. 

Rapid7 observations

Rapid7 Labs has become aware of a new exploitation tool that streamlines the extraction of sensitive data from vulnerable MongoDB instances. This utility introduces a graphical user interface that allows an attacker to either batch-dump 10MB of memory or monitor the extraction process via a live visual feed. Rapid7 Labs has confirmed the tool operates as described, as demonstrated in the video below.

Detection and Hunting

Velociraptor 

Velociraptor published a Linux.Detection.CVE202514847.MongoBleed hunting artifact written by Eric Capuano designed to detect indicators related to CVE-2025-14847 memory leakage activity. This artifact enables defenders to proactively identify suspicious network or process behaviors consistent with mangled Zlib protocol abuse.

Updates

• December 29, 2025: Initial publication

• December 29, 2025: "Rapid7 Observations" section added with video

• December 29, 2025: Added exploitation confirmation