Severe MongoDB Vulnerability CVE-2025-14847 Exploited in the Wild

THE THREAT (Executive Summary)

A recently disclosed vulnerability affecting multiple versions of MongoDB has been reported as actively exploited in real-world attacks. Tracked as CVE-2025-14847 (CVSS score: 8.7), the flaw enables an unauthenticated attacker to access sensitive data by sending specially crafted network packets. Successful exploitation may result in the disclosure of sensitive information residing in memory, including user credentials, secrets, tokens, and authentication keys, potentially leading to significant data breaches.

Following the disclosure, cybersecurity firms released technical analysis and Proof-of-Concept (PoC) exploit code with active exploitation reported soon after. Organizations operating vulnerable, internet-facing MongoDB instances are strongly advised to remediate the issue immediately by applying the appropriate security patches.

What we’re doing about it

• eSentire's Threat Response Unit (TRU) has created new eSentire MDR for Network rules to identify exploitation attempts
• eSentire Managed Vulnerability Service (MVS) has plugins in place to identify devices vulnerable to CVE-2025-14847
• eSentire’s Threat Intelligence Team is actively tracking the topic for additional details and detection opportunities

What you should do about it

• Upgrade to MongoDB 8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32, or 4.4.30
• If upgrade is not immediately feasible:
  • Disable the zlib compression on the MongoDB server
  • Use alternative compression methods, such as Zstandard or Snappy
• Restrict access to management infrastructure to trusted IP addresses only
• If compromise is detected, rotate the exposed credentials, secrets, keys, or tokens

Additional information

CVE-2025-14847 arises from mismatched length fields in zlib-compressed protocol headers on the MongoDB server. A critical fix was released concurrently with the vulnerability disclosure on December 19th, 2025. OX Security provided technical details explaining that the fix resolves an issue in the zlib message decompression process, where the database could be forced to allocate or process undersized memory buffers during network message decompression. This flaw could result in uninitialized heap memory being exposed, leaking sensitive in-memory data remotely. Wiz reported that the vulnerability also affects the Ubuntu rsync package, however no exploitation activity has been observed to date.

Elastic Security researcher released a PoC exploit for the vulnerability, dubbed MongoBleed, which enables unauthenticated memory reads on a MongoDB server. Security researcher Kevin Beaumont noted that the exploit code was functional and required only the target MongoDB server’s IP address to retrieve sensitive data. Shortly after the PoC release, threat actors claimed to have exploited the flaw to compromise Ubisoft’s Rainbow Six Siege online platform. The reported incident resulted in the banning and unbanning of players, manipulation of in-game moderation feeds, and the distribution of large amounts of in-game currency and cosmetic items to accounts globally. While these exploitation claims remain unverified, the incident led to a temporary shutdown of the game servers.

Security researchers have developed detection strategies, including MongoBleed detector tool and rules based on the available PoC exploit code. While these measures may help identify potential exploitation, upgrading vulnerable MongoDB instances to secure versions remains critical. Censys reported that more than 87,000 potentially vulnerable MongoDB instances are exposed to the internet, and Wiz indicated that 42% of cloud environments contain at least one vulnerable MongoDB instance, underscoring the potential for widespread exploitation.

If upgrading is not immediately feasible, MongoDB recommends disabling zlib compression on the server and using alternative compression methods such as Snappy or Zstandard (zstd). As the vulnerability can be exploited prior to authentication and without user interaction, Internet-facing instances remain at heightened risk. Organizations are therefore advised to restrict server access to trusted IP addresses only.

References:

[1] https://jira.mongodb.org/browse/SERVER-115508
[2] https://nvd.nist.gov/vuln/detail/CVE-2025-14847
[3] https://www.ox.security/blog/attackers-could-exploit-zlib-to-exfiltrate-data-cve-2025-14847/#technical_analysis
[4] https://github.com/joe-desimone/mongobleed/
[5] https://x.com/vxunderground/status/2005008887234048091
[6] https://github.com/facebook/zstd
[7] https://github.com/google/snappy
[8] https://www.wiz.io/blog/mongobleed-cve-2025-14847-exploited-in-the-wild-mongodb
[9] https://doublepulsar.com/merry-christmas-day-have-a-mongodb-security-incident-9537f54289eb
[10] https://github.com/Neo23x0/mongobleed-detector
[11] https://blog.ecapuano.com/p/hunting-mongobleed-cve-2025-14847
[12] https://censys.com/advisory/cve-2025-14847