CISA confirms ‘MongoBleed’ is under active exploitation, and the worst part is hackers are now accessing passwords and API keys using one simple trick

The US Cybersecurity and Infrastructure Security Agency has confirmed that the high-severity “MongoBleed” vulnerability is currently under active exploitation, as per The Register. This is absolutely awful news for any organization that took time off over the holidays, especially since this flaw basically lets hackers scoop up user passwords, API keys, and other incredibly sensitive data.

Security experts are calling this development “basically Heartbleed for MongoDB,” and honestly, that comparison tells you everything you need to know about how serious this is. We’re talking about a CVSS 8.7 vulnerability, officially tracked as CVE-2025-14847, that affects a massive range of widely used MongoDB Server versions which makes the recent South Korean private camera breach look small.

The core problem, which security researchers identified back on December 15, is a nightmare scenario stemming from the server’s network transport layer. The flaw lies specifically in how MongoDB handles zlib-compressed protocol headers. In simple terms, there’s a serious mismatch in the length fields. If an attacker sends a specially malformed packet to a vulnerable server, they can force the system to read uninitialized heap memory.

This is exactly the type of vulnerability that keeps system administrators up at night

Think of it this way: the MongoDB message compressor was coded to return the output length instead of just the actual length of the decompressed data. This simple mistake means the system can be tricked into spilling whatever random data happened to be sitting in the allocated memory buffer, instead of just the clean, decompressed information. Oops. That “spill” is where the unauthenticated remote attacker gets to feast on your user information, database contents, and those precious API keys.

The government agency noted that this type of issue is a frequent target for malicious actors and “poses significant risks to the federal enterprise.” If your MongoDB Server is exposed directly to the internet, you’re an open target. Even if your server is tucked away inside a private network, researchers pointed out that if an attacker manages to gain a foothold through lateral movement, they can ferret out and pluck those private servers too.

The timing couldn’t have been worse. Proofs of concept for this exploit emerged right around Christmas week, when many security teams were enjoying their well-deserved time off. This is precisely when attackers strike. Notably, hackers recently tricked major tech companies like Apple, Amazon, and Charter Communications into giving away sensitive customer data.

As one security firm noted, “Although the attacker might need to send a large amount of requests to gather the full database, and some data might be meaningless, the more time an attacker has the more information could be gathered.”

That extra time over the long holiday weekend gave them a huge advantage in scraping data. The MongoDB maker did patch the vulnerability shortly after it was identified in December. However, if you haven’t applied that patch yet, you are at risk right now. The official advice is crystal clear: affected users need to upgrade to fixed releases immediately.