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CVE-2026-126838

Rust Driver public Client Debug output exposes CSFLE KMS master-key material

  • Medium 5.7

Description

A MongoDB Rust Driver component that holds client-side field level encryption settings includes key management service credential material in its diagnostic formatting output without redaction. An application that records or displays this formatted output may place that material where a party with read access to the application's diagnostic output can see it, which may result in unintended disclosure of key material.

Key facts

Published
12 Nov 2026
Last changed
13 Nov 2026
Assigned by
mongodb
EPSS
0.073% likely to be exploited in the next 30 days, higher than 0.06% of CVEs (scores for 15 Nov 2026)
SSVC (CISA)
Exploitation: none; Automatable: no; Technical impact: partial

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

  • 5.7CVSS 4.0, Mediumfrom the CNA (mongodb)CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
  • 5.5CVSS 3.1, Mediumfrom the CNA (mongodb)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

No explicit remediation statement is available on this page yet. Consult the original record and vendor references before choosing a fix.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

VendorProductVersions
MongoDBRust Driver
  • Default status: unaffected
  • 3.9.0 up to but excluding 3.9.1 (affected)
  • 3.8.0 up to but excluding 3.8.2 (affected)
  • 3.7.0 (affected)
  • 3.6.0 (affected)
  • 3.5.0 up to but excluding 3.5.2 (affected)
  • 3.4.0 up to but excluding 3.4.1 (affected)
  • 3.3.0 (affected)
  • 3.2.0 up to but excluding 3.2.5 (affected)
  • 3.1.0 up to but excluding 3.1.1 (affected)
  • 3.0.0 up to but excluding 3.0.1 (affected)
  • 2.8.0 up to but excluding 2.8.2 (affected)
  • 2.7.0 up to but excluding 2.7.1 (affected)
  • 2.6.0 up to but excluding 2.6.1 (affected)
  • 2.5.0 (affected)
  • 2.4.0 (affected)

Timeline

  1. 12 Nov 2026 Published

Weakness

References