How Eden Protects Against Mongobleed (CVE-2025-14847)
January 2, 2026 · Eden Security Team
Tags: announcement, release
On December 26, 2025, security researchers disclosed CVE-2025-14847, a critical vulnerability in MongoDB's wire protocol. Dubbed "Mongobleed" (after the infamous Heartbleed), it allows unauthenticated attackers to read server memory remotely. It affects MongoDB versions 3.6 through 8.2.2.
Eden users are protected. Our MongoDB proxy blocks Mongobleed exploitation attempts before they reach your database servers.
What's the Vulnerability?
Mongobleed exploits a flaw in how MongoDB handles compressed messages. When MongoDB decompresses a message, it trusts the uncompressedSize field in the header without validation.
An attacker can craft a message where the declared size exceeds the actual data. MongoDB allocates a buffer based on the declared size, writes less data than expected, and subsequent reads expose uninitialized heap memory.
The scary part: this happens before authentication. Any exposed MongoDB server is vulnerable.
How Eden Blocks It
Our MongoDB wire protocol parser validates messages before they reach your database:
Length consistency — Every message header must match the actual bytes received. Mismatched lengths (the signature of a Mongobleed attack) are rejected immediately.
Size bounds — We cap uncompressed sizes at 256 MB. Legitimate MongoDB operations rarely exceed a few megabytes.
Compression validation — For zlib-compressed messages, we validate header integrity and compression ratios.
Streaming limits — We decompress with incremental size checking to prevent zip bomb attacks.
Performance Impact
Less than 100 microseconds added latency. The validation runs in the proxy's hot path using zero-copy parsing—no heap allocations for valid messages.
What You Should Do
While Eden protects proxied connections, we recommend:
- Patch MongoDB servers to 8.2.3+, 8.0.17+, 7.0.28+, 6.0.27+, 5.0.32+, or 4.4.30+
- Disable zlib compression if not needed:
networkMessageCompressors: snappy,zstd - Route all traffic through Eden for defense-in-depth
- Monitor for exploitation attempts via Eden's security logging
Timeline
- December 26, 2025: CVE publicly disclosed
- December 27, 2025: Eden v0.13.1 released with protection
- December 29, 2025: CISA adds CVE to Known Exploited Vulnerabilities catalog
Database proxies like Eden are a critical security layer. By validating protocol messages before they reach your database, we can block entire classes of attacks—even zero-days.