CVE-2026-93393 Heap overflow via oversized decrypted TLS record sequence in Windows Secure Channel stream
A remote attacker can trigger a heap overflow in the MongoDB C Driver's Windows TLS backend, potentially leading to code execution or information disclosure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-93393?
CVE-2026-93393 is a critical memory corruption vulnerability in MongoDB Inc. C Driver, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A heap-based buffer overflow exists in the TLS transport layer of the MongoDB C Driver when built with the Windows platform TLS backend. A remote endpoint that the client connects to can cause the driver to write uncontrolled data outside the bounds of a heap allocation while processing incoming encrypted traffic after the TLS handshake completes. No authentication or user interaction is required, because the affected processing occurs before any application-level authentication completes. Triggering this issue may lead to memory corruption in the client process, disclosure of adjacent heap memory, or termination of the process.
Weakness: CWE-787
Which versions are affected by CVE-2026-93393?
It affects 1 product.
Products include Mongodb C Driver.
How do I fix CVE-2026-93393?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-93393 being exploited?
There is no known exploitation of CVE-2026-93393 in the wild and no public exploit code.
Other vulnerabilities in MongoDB Inc. C Driver
- CVE-2026-6691 MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow
- CVE-2026-84964 Heap corruption via OCSP request double free from crafted multi-URL certificate in TLS client
- CVE-2024-7553 Accessing Untrusted Directory May Allow Local Privilege Escalation
- CVE-2026-93395 Integer Underflow → Heap Out-of-Bounds Read in `bson_new_from_buffer()
- CVE-2025-12119 Bulk write with options may read invalid memory
Sources
Also known as DEBIAN-CVE-2026-93393, GHSA-x65h-hw7w-mq6w, UBUNTU-CVE-2026-93393.