New MongoDB Flaw Lets Unauthenticated Attackers Read Uninitialized Memory
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2025-14847 | Unauthenticated Heap Memory Disclosure in MongoDB Server (MongoBleed) CVE-2025-14847 ('MongoBleed') is an improper handling of length parameter inconsistency (CWE-130) in MongoDB Server's processing of Zlib-compressed protocol headers, where mismatched length fields cause the server to return uninitialized heap memory. An unauthenticated remote client can trigger the leak by sending specially crafted compressed protocol messages to a vulnerable server, with no credentials, user interaction, or complex conditions required. The impact is confidentiality-only: an attacker can harvest fragments of the server's heap memory, which may contain sensitive in-memory data such as documents, credentials, or keys, reflected in the High confidentiality rating in the 8.7 CVSS 4.0 score. Virtually every MongoDB Server release from 3.6 through 8.2 is affected unless updated to the fixed patch levels (e.g., 8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32, 4.4.30), so the potentially exposed population is extremely large. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2025-12-29, is reported as actively exploited in the wild worldwide (including a joint US-Australia advisory), and carries a very high EPSS of 83.2%, making patching urgent. Do: Upgrade MongoDB Server immediately to the fixed release for your branch: 8.2.3+, 8.0.17+, 7.0.28+, 6.0.27+, 5.0.32+, or 4.4.30+; 3.6, 4.0, and 4.2 deployments are affected in all versions and should be moved to a patched release or retired per MongoDB guidance. Until patched, restrict network access to MongoDB to trusted clients and consider disabling Zlib network compression as an interim mitigation, and review logs for unauthenticated client connections. Because the flaw is on CISA's KEV catalog with active exploitation observed (including ransomware-adjacent tracking), apply mitigations per BOD 22-01 timelines or discontinue use of affected unpatched instances. | 8.7 | 83% | KEV PoC ×3 |
| masstens of thousands of MongoDB instances directly exposed to the internet, within millions of total deployments worldwide (estimate) |
Full article318 words · extracted from thehackernews.com · click to collapse
Ravie LakshmananDec 27, 2025Database Security / Vulnerability
A high-severity security flaw has been disclosed in MongoDB that could allow unauthenticated users to read uninitialized heap memory.
The vulnerability, tracked as CVE-2025-14847 (CVSS score: 8.7), has been described as a case of improper handling of length parameter inconsistency, which arises when a program fails to appropriately tackle scenarios where a length field is inconsistent with the actual length of the associated data.
"Mismatched length fields in zlib compressed protocol headers may allow a read of uninitialized heap memory by an unauthenticated client," according to a description of the flaw in CVE.org.
The flaw impacts the following versions of the database -
- MongoDB 8.2.0 through 8.2.3
- MongoDB 8.0.0 through 8.0.16
- MongoDB 7.0.0 through 7.0.26
- MongoDB 6.0.0 through 6.0.26
- MongoDB 5.0.0 through 5.0.31
- MongoDB 4.4.0 through 4.4.29
- All MongoDB Server v4.2 versions
- All MongoDB Server v4.0 versions
- All MongoDB Server v3.6 versions
The issue has been addressed in MongoDB versions 8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32, and 4.4.30.
"An client-side exploit of the Server's zlib implementation can return uninitialized heap memory without authenticating to the server," MongoDB said. "We strongly recommend upgrading to a fixed version as soon as possible."
If immediate update is not an option, it's recommended to disable zlib compression on the MongoDB Server by starting mongod or mongos with a networkMessageCompressors or a net.compression.compressors option that explicitly omits zlib. The other compressor options supported by MongoDB are snappy and zstd.
"CVE-2025-14847 allows a remote, unauthenticated attacker to trigger a condition in which the MongoDB server may return uninitialized memory from its heap," OP Innovate said. "This could result in the disclosure of sensitive in-memory data, including internal state information, pointers, or other data that may assist an attacker in further exploitation."
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