CVE-2026-84964 Heap corruption via OCSP request double free from crafted multi-URL certificate in TLS client
A malicious trusted TLS endpoint can trigger a double free in the MongoDB C Driver, causing the client application to crash.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-84964?
CVE-2026-84964 is a high-severity use after free vulnerability in MongoDB C Driver, published on 3 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A double free in the OpenSSL-based TLS certificate revocation checking path of the MongoDB C Driver can be reached by a TLS endpoint that the client already trusts. During the handshake, specially formed certificate data can cause the same heap object to be released twice. An unauthenticated party acting as the trusted endpoint may cause the connecting client application to terminate unexpectedly.
Weakness: CWE-415
Which versions are affected by CVE-2026-84964?
It affects 1 product.
Products include Mongodb C Driver.
How do I fix CVE-2026-84964?
Upgrade to a fixed version.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-84964 being exploited?
There is no known exploitation of CVE-2026-84964 in the wild and no public exploit code.
Other vulnerabilities in MongoDB C Driver
- CVE-2026-93393 Heap overflow via oversized decrypted TLS record sequence in Windows Secure Channel stream
- CVE-2026-6691 MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow
- 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-2026-84964, UBUNTU-CVE-2026-84964.