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CVE-2026-96746

Heap buffer overflow via mid-scan command list growth in client topology monitoring

8.3 HighFix available

An out-of-bounds write in the connection-monitoring logic of the MongoDB C Driver may allow an unauthenticated party who controls name resolution and the responses of the hosts named in a client's connection string to write beyond the end of a heap buffer. This may cause the application using the driver to terminate unexpectedly.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
High

Exploit likelihood

0.40%Unchanged since Sep 25, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.3

Heap buffer overflow via mid-scan command list growth in client topology monitoring

An out-of-bounds write in the connection-monitoring logic of the MongoDB C Driver may allow an unauthenticated party who controls name resolution and the responses of the hosts named in a client's connection string to write beyond the end of a heap buffer. This may cause the application using the driver to terminate unexpectedly.

Record
CVE-2026-96746
CVSS 4.0
8.3 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-787
Updated
2026-11-02
EUVDEUVD-2026-86263 8.3

An out-of-bounds write in the connection-monitoring logic of the MongoDB C Driver may allow an unauthenticated party who controls name resolution and the responses of the hosts named in a client's connection string to write beyond the end of a heap buffer. This may cause the application using the driver to terminate unexpectedly.

Record
EUVD-2026-86263
CVSS 4.0
8.3 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
NVD 8.3

An out-of-bounds write in the connection-monitoring logic of the MongoDB C Driver may allow an unauthenticated party who controls name resolution and the responses of the hosts named in a client's connection string to write beyond the end of a heap buffer. This may cause the application using the driver to terminate unexpectedly.

Record
CVE-2026-96746
CVSS 4.0
8.3 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/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
6.5 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness
CWE-787
Updated
2026-11-02
OSV 8.3

Heap buffer overflow via mid-scan command list growth in client topology monitoring

An out-of-bounds write in the connection-monitoring logic of the MongoDB C Driver may allow an unauthenticated party who controls name resolution and the responses of the hosts named in a client's connection string to write beyond the end of a heap buffer. This may cause the application using the driver to terminate unexpectedly.

Record
CVE-2026-96746
CVSS 4.0
8.3 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-787
Updated
2026-11-02
OSVDEBIAN-CVE-2026-96746 8.3

An out-of-bounds write in the connection-monitoring logic of the MongoDB C Driver may allow an unauthenticated party who controls name resolution and the responses of the hosts named in a client's connection string to write beyond the end of a heap buffer. This may cause the application using the driver to terminate unexpectedly.

Record
DEBIAN-CVE-2026-96746
CVSS 4.0
8.3 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/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-2026-96746 8.3

An out-of-bounds write in the connection-monitoring logic of the MongoDB C Driver may allow an unauthenticated party who controls name resolution and the responses of the hosts named in a client's connection string to write beyond the end of a heap buffer. This may cause the application using the driver to terminate unexpectedly.

Record
UBUNTU-CVE-2026-96746
CVSS 4.0
8.3 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
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
pymongo
Ubuntu:14.04:LTS
All versions, plus listed versions
2.6-12.6.2-12.6.3-12.6.3-1build1
None known
pymongo
Ubuntu:Pro:16.04:LTS
All versions, plus listed versions
3.0.3-13.2-13.2-1build13.2-1ubuntu0.1~esm1
None known
pymongo
Ubuntu:Pro:18.04:LTS
All versions, plus listed versions
3.4.0-1build23.6.1+dfsg1-13.6.1+dfsg1-1ubuntu0.1~esm1
None known
pymongo
Ubuntu:20.04:LTS
All versions, plus listed versions
3.7.1-1.13.7.1-1.1build13.10.1-0ubuntu23.10.1-0ubuntu2.1
None known
pymongo
Ubuntu:22.04:LTS
All versions, plus listed versions
3.11.0-1build23.11.0-1build33.11.0-1build43.11.0-1ubuntu0.22.04.1
None known
pymongo
Ubuntu:24.04:LTS
All versions, plus listed versions
3.11.0-1build63.11.0-1build73.11.0-1build83.11.0-1ubuntu0.24.04.1
None known
pymongo
Ubuntu:26.10
All versions, plus listed versions
4.16.0-1build14.17.0-1
None known
pymongo
Ubuntu:26.04:LTS
All versions, plus listed versions
4.10.1-64.15.3-14.15.3-24.15.5-14.16.0-14.16.0-1build1
None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, NVD, OSV

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

In short

CVE-2026-96746 is a high vulnerability (CVSS 8.3) in Mongodb C Driver, published September 24, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.40%, the 34th percentile. Fixed in mongo-c-driver 2.5.5-1.

References

This page doesn't list everything

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

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