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CVE-2026-93393

Heap overflow via oversized decrypted TLS record sequence in Windows Secure Channel stream

9.2 CriticalFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.47%Up 0.2 points since Sep 18, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.2

Heap overflow via oversized decrypted TLS record sequence in Windows Secure Channel stream

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.

Record
CVE-2026-93393
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-787
Updated
2026-11-02
EUVDEUVD-2026-82435 9.2

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.

Record
EUVD-2026-82435
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-x65h-hw7w-mq6w 9.2

A heap-based buffer overflow exists in the TLS transport layer of the MongoDB C Driver when built...

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, or an attacker able to impersonate or redirect the client's connection, can cause the driver to write attacker-supplied data outside the bounds of a heap allocation while processing incoming encrypted traffic. No authentication or user interaction is required, because the affected processing occurs before any application-level authentication completes. Successful exploitation may lead to memory corruption in the client process, disclosure of adjacent heap memory, or termination of the process.

Record
GHSA-x65h-hw7w-mq6w
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-787
Updated
2026-11-02
NVD 9.2

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.

Record
CVE-2026-93393
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-787
Updated
2026-11-02
OSVALPINE-CVE-2026-93393 9.2

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.

Record
ALPINE-CVE-2026-93393
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-03
OSV 9.2

Heap overflow via oversized decrypted TLS record sequence in Windows Secure Channel stream

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.

Record
CVE-2026-93393
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-787
Updated
2026-11-02
OSVDEBIAN-CVE-2026-93393 9.2

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.

Record
DEBIAN-CVE-2026-93393
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02
OSVUBUNTU-CVE-2026-93393 9.2

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.

Record
UBUNTU-CVE-2026-93393
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
mongo-c-driver
Alpine:v3.24
before 1.30.14-r0
1.30.14-r0
mongo-c-driver
Debian:12
All versions, plus listed versions
1.23.1-11.23.1-1+deb12u11.23.1-1+deb12u21.23.1-1+deb12u31.24.1-1
Show 45 moreShow less
1.24.2-11.24.3-11.24.4-11.25.0-11.25.1-11.25.2-11.25.4-11.25.4-1.1~exp11.26.0-11.26.0-1.11.26.0-1.1~exp11.26.1-11.26.2-11.27.0-11.27.1-11.27.2-11.27.3-11.27.4-11.27.5-11.27.6-11.28.0-11.28.1-11.29.0-11.29.1-11.29.2-11.30.0-11.30.1-11.30.2-11.30.3-11.30.4-12.0.2-12.1.0-12.1.1-12.1.2-12.2.0-12.2.1-12.2.2-12.2.3-12.2.4-12.3.0-12.3.1-12.3.2-12.3.3-12.4.0-12.5.0-1
None known
mongo-c-driver
Debian:13
All versions, plus listed versions
1.30.4-11.30.4-1+deb13u11.30.4-1+deb13u21.30.4-1+deb13u32.0.2-1
Show 18 moreShow less
2.1.0-12.1.1-12.1.2-12.2.0-12.2.1-12.2.2-12.2.3-12.2.4-12.3.0-12.3.1-12.3.2-12.3.3-12.4.0-12.5.0-12.5.1-12.5.2-12.5.3-12.5.5-1
None known
mongo-c-driver
Debian:14
before 2.5.5-1, plus listed versions
1.30.4-12.0.2-12.1.0-12.1.1-12.1.2-1
Show 14 moreShow less
2.2.0-12.2.1-12.2.2-12.2.3-12.2.4-12.3.0-12.3.1-12.3.2-12.3.3-12.4.0-12.5.0-12.5.1-12.5.2-12.5.3-1
2.5.5-1
mongo-c-driver
Ubuntu:Pro:20.04:LTS
All versions, plus listed versions
1.15.0-11.15.1-11.15.2-11.16.0-11.16.1-11.16.1-1build11.16.1-1build21.16.1-1ubuntu0.1~esm1
None known
mongo-c-driver
Ubuntu:Pro:22.04:LTS
All versions, plus listed versions
1.18.0-11.19.1-11.19.2-11.20.0-11.20.0-1build1
Show 4 moreShow less
1.20.1-11.21.0-11.21.0-1build11.21.0-1ubuntu0.1~esm1
None known
mongo-c-driver
Ubuntu:Pro:24.04:LTS
All versions, plus listed versions
1.24.3-11.24.4-11.25.1-11.25.2-11.25.4-1
Show 4 moreShow less
1.26.0-11.26.0-1.1ubuntu11.26.0-1.1ubuntu21.26.0-1.1ubuntu2+esm1
None known
mongo-c-driver
Ubuntu:26.10
All versions, plus listed versions
2.2.2-12.3.1-12.3.2-12.3.3-1build12.5.0-1
None known
mongo-c-driver
Ubuntu:26.04:LTS
All versions, plus listed versions
1.30.4-1ubuntu12.2.0-12.2.1-12.2.2-1
None known

History

History
RecordedChangedSources
affected, aliases, referencesOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-93393 is a critical vulnerability (CVSS 9.2) in Mongodb C Driver, published September 17, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.47%, the 40th percentile. Fixed in mongo-c-driver 1.30.14-r0.

References

This page doesn't list everything

Left out here: 4 versions. The JSON record has them.

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