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MongoDB MongoBleed Vulnerability (CVE-2025-14847): Critical Unauthenticated Memory Leak and Data Exposure Risk

  • Rescana
  • 23 hours ago
  • 5 min read
Image for post about New MongoDB Flaw Lets Unauthenticated Attackers Read Uninitialized Memory

Executive Summary

A newly disclosed critical vulnerability, CVE-2025-14847 (commonly referred to as "MongoBleed"), has been identified in MongoDB. This flaw enables unauthenticated, remote attackers to read uninitialized heap memory from affected MongoDB servers when zlib compression is enabled. The vulnerability is present across a broad spectrum of MongoDB versions and is exploitable over the network, potentially exposing sensitive in-memory data such as credentials, session tokens, or application secrets. The attack requires no authentication or user interaction, making it a high-risk issue for any organization running vulnerable MongoDB instances. This advisory provides a comprehensive technical breakdown, exploitation context, threat actor analysis, affected versions, mitigation guidance, and authoritative references to support your risk management and incident response efforts.

Threat Actor Profile

At the time of this report, there is no public attribution of CVE-2025-14847 exploitation to any specific Advanced Persistent Threat (APT) groups. No sector-specific or country-specific targeting has been reported. However, given the critical nature of the vulnerability, its unauthenticated attack vector, and the widespread use of MongoDB in cloud, SaaS, and enterprise environments, it is highly likely that both opportunistic cybercriminals and sophisticated threat actors will seek to leverage this flaw in future campaigns.

The vulnerability aligns with several tactics and techniques in the MITRE ATT&CK framework, including T1046 (Network Service Scanning), T1005 (Data from Local System), and T1210 (Exploitation of Remote Services). These techniques are commonly employed by both financially motivated attackers and state-sponsored groups to gain initial access, perform reconnaissance, and exfiltrate sensitive data.

Organizations should remain vigilant for signs of exploitation and monitor threat intelligence sources for updates on potential APT activity related to MongoBleed.

Technical Analysis of Malware/TTPs

CVE-2025-14847 is a high-severity information disclosure vulnerability in the network transport layer of MongoDB. The flaw arises from improper handling of length parameter inconsistencies in the zlib compression protocol headers. When a specially crafted compressed payload is sent to a vulnerable MongoDB server, the server may miscalculate the length of the decompressed data. This miscalculation can cause the server to return fragments of uninitialized heap memory in its response, which may contain sensitive information.

The vulnerability is triggered during the decompression process, specifically before any authentication checks are performed. This means that any remote attacker with network access to the MongoDB service can exploit the flaw, provided zlib compression is enabled. The attack vector is purely network-based, and the exploit complexity is low, requiring only the ability to send malformed compressed frames to the server.

The technical root cause is a mismatch between the declared and actual lengths in the zlib-compressed protocol headers. When the server processes a compressed message with inconsistent length fields, it may inadvertently include uninitialized memory in its response payload. This memory can contain arbitrary data from the server's heap, including potentially sensitive application data, cryptographic material, or internal state information.

The vulnerability is particularly dangerous because it can be exploited without authentication, and it affects both self-managed and cloud-hosted MongoDB deployments. The only prerequisite is that the server must be accessible over the network and have zlib compression enabled, which is a common configuration in many production environments.

Security researchers from Aikido Security and OP Innovate have independently confirmed the exploitability of this flaw. The issue was initially discovered through regression testing and has been addressed in recent patches by the MongoDB development team. The vulnerability has been assigned a CVSS score of 8.7, reflecting its high impact and ease of exploitation.

In summary, CVE-2025-14847 represents a significant risk to organizations using affected versions of MongoDB with zlib compression enabled. Immediate action is required to mitigate the threat and prevent potential data leakage.

Exploitation in the Wild

As of the latest available intelligence, there is no confirmed evidence of widespread exploitation of CVE-2025-14847 ("MongoBleed") in the wild. However, the vulnerability's low complexity, unauthenticated attack vector, and the prevalence of MongoDB in enterprise and cloud environments make it an attractive target for both opportunistic and targeted attackers.

Security researchers have developed proof-of-concept exploits that reliably trigger the vulnerability by sending malformed zlib-compressed frames to vulnerable MongoDB instances. These exploits demonstrate that attackers can extract arbitrary fragments of uninitialized heap memory from the server's responses. The leaked data may include sensitive information such as database credentials, session tokens, or internal application data.

Indicators of compromise associated with exploitation attempts include unusual network traffic to MongoDB ports (default 27017) from untrusted sources, especially traffic containing zlib-compressed payloads. Organizations should also monitor for unexpected memory fragments or data leakage in MongoDB responses, as well as access logs showing unauthenticated requests with compressed payloads.

While no public exploit code has been released as of this advisory, the technical details are widely available, and the risk of mass exploitation is expected to increase as awareness grows. Organizations are strongly advised to apply patches or implement mitigations without delay.

Victimology and Targeting

No specific APT group, sector, or country targeting has been reported as of December 2025. The vulnerability is likely to be leveraged by both opportunistic and targeted attackers due to its ease of exploitation and the prevalence of MongoDB in cloud, SaaS, and enterprise environments globally.

Mitigation and Countermeasures

The most effective mitigation is to upgrade to the latest patched version of MongoDB for your release line. The fixed versions are 8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32, and 4.4.30. For organizations running MongoDB 4.2, 4.0, or 3.6, upgrading to a supported and patched version is mandatory, as no fixes are available for these legacy releases.

If immediate upgrade is not feasible, a temporary mitigation is to disable zlib compression. This can be achieved by starting mongod or mongos with the networkMessageCompressors or net.compression.compressors options, omitting zlib and using alternative compressors such as snappy or zstd.

Additionally, organizations should restrict network access to MongoDB instances using firewalls, security groups, or Kubernetes NetworkPolicies. It is critical to ensure that MongoDB is not accessible from the public internet unless absolutely necessary. Regularly review access logs for signs of unauthenticated requests with compressed payloads and monitor for unusual data leakage in server responses.

Implementing these mitigations will significantly reduce the risk of exploitation and data exposure associated with CVE-2025-14847.

References

For further technical details and authoritative guidance, consult the following resources:

About Rescana

Rescana is committed to helping organizations proactively manage third-party and supply chain cyber risk. Our advanced TPRM platform empowers you to continuously monitor, assess, and mitigate vulnerabilities across your digital ecosystem. We provide actionable intelligence, automated risk scoring, and deep visibility into your vendor landscape, enabling you to stay ahead of emerging threats and regulatory requirements. For any questions about this advisory or to learn how Rescana can support your cybersecurity program, please contact us at ops@rescana.com.

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