CVE Intelligence
High Memory corruption

CVE-2026-93393 — 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.

Published Sep 17, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: mongodb

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.5% (30-day exploitation probability)+6
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.47%
ahead of 39% of scored CVEs · Oct 15, 2026
Affects
Mongodb
C Driver
CVSS base
8.1
High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Mongodb C Driver).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Mongodb C Driver ≥ 1.10.0 and < 1.30.11≥ 2.2.0 and < 2.5.4 Vulnerable NIST National Vulnerability Database
Mongodb C Driver version 2.4.0≥ 2.3.0 and ≤ 2.3.3≥ 2.2.0 and ≤ 2.2.4≥ 2.1.0 and ≤ 2.1.2≥ 2.0.0 and ≤ 2.0.2≥ 1.30.0 and ≤ 1.30.8≥ 1.29.0 and ≤ 1.29.2≥ 1.28.0 and ≤ 1.28.1
and 4 more ≥ 1.27.0 and ≤ 1.27.6≥ 1.26.0 and ≤ 1.26.2≥ 1.25.0 and ≤ 1.25.4≥ 1.24.0 and ≤ 1.24.4
Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
9.2 CVSS 4.0 Critical — — cna@mongodb.com via NIST National Vulnerability Database
9.2 CVSS 4.0 Critical — — mongodb via CVE Program (cve.org) e CISA ADP
8.1 CVSS 3.1 High 2.2 5.9 cna@mongodb.com via NIST National Vulnerability Database
8.1 CVSS 3.1 High — — mongodb via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: cna@mongodb.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-787 · Out-of-bounds Write

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · mongodb inc./c driver
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 15, 2026
  • CVSS changed · 8.1
    Oct 15, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 17, 2026 · mongodb

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

1 on the record

Elsewhere on this site

Mongodb
every CVE for this vendor
Memory corruption
same class
CWE-787
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-106438 Silent Decimal128 value corruption via incorrect exactness check in MongoDB C Driver 7d
  • CVE-2026-106437 Out-of-bounds read and write via undersized BSON buffer reservation in MongoDB C Driver 7d
  • CVE-2026-106431 One-byte heap buffer overflow in BSON bulk document writer in MongoDB C Driver 7d
  • CVE-2026-106428 Out-of-bounds read in SCRAM response parsing in MongoDB C Driver 7d
  • CVE-2026-106430 Query and rename target confusion via embedded NUL truncation in MongoDB C++ Driver 7d
  • CVE-2026-96746 Heap buffer overflow via mid-scan command list growth in client topology monitoring 21d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-93393 is "Heap overflow via oversized decrypted TLS record sequence in Windows Secure Channel stream", rated High. It affects C Driver (Mongodb); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.1 describes technical severity. EPSS 0.47% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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