Bug 2538905 (CVE-2026-93393)

Summary: CVE-2026-93393 mongo-c-driver: Heap overflow via oversized decrypted TLS record sequence in Windows Secure Channel stream
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: urgent Docs Contact:
Priority: urgent    
Version: unspecifiedCC: jburati
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in mongo-c-driver. A heap-based buffer overflow exists in the Transport Layer Security (TLS) transport layer when compiled with the Windows platform TLS backend. A remote server can exploit this flaw by sending crafted encrypted traffic after the TLS handshake completes, causing the driver to write data outside the boundaries of allocated heap memory before application-level authentication takes place. Successful exploitation may lead to client process memory corruption, unauthorized disclosure of adjacent memory, or a Denial of Service (DoS) via application crash.
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Description OSIDB Bzimport 2026-09-22 21:08:35 UTC 
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.