Security researchers have disclosed a high-severity flaw in MongoDB that could allow unauthenticated users to read uninitialized heap memory.
Vulnerability Overview and Technical Details
The vulnerability, tracked as CVE-2025-14847 and assigned a CVSS score of 8.7, stems from improper handling of length parameter inconsistencies. Specifically, this issue occurs when software fails to properly manage situations where a length field does not match the actual size 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 affects the following MongoDB releases:
- 8.2.0 through 8.2.3
- 8.0.0 through 8.0.16
- 7.0.0 through 7.0.26
- 6.0.0 through 6.0.26
- 5.0.0 through 5.0.31
- 4.4.0 through 4.4.29
- All v4.2 versions
- All v4.0 versions
- All v3.6 versions
MongoDB has resolved the issue in versions 8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32, and 4.4.30.
Vendor Response and Mitigation Guidance
MongoDB confirmed that attackers could exploit the flaw remotely without authentication.
“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 an immediate upgrade is not possible, administrators should disable zlib compression on the MongoDB Server. To do so, they can start mongod or mongos with a networkMessageCompressors or net.compression.compressors option that explicitly omits zlib. MongoDB also supports snappy and zstd as alternative compression options.
Potential Security Impact
Security firm OP Innovate warned that the vulnerability poses a significant risk to exposed systems.
“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.”
Source: TheHackerNews
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