CVE-2026-18691 (GCVE-0-2026-18691)

Vulnerability from cvelistv5 – Published: 2026-08-11 18:46 – Updated: 2026-08-11 20:22
VLAI
Title
Improper Authentication in MongoDB Intra-Cluster Connections Allows Credential Exposure
Summary
An issue in MongoDB Server's intra-cluster connection setup could allow a party with suitable network access to influence which authentication mechanism is used when one replica set member connects to another. Under certain conditions, this could cause the cluster's shared internal credential to be transmitted in a less-protected form, potentially allowing that credential to be recovered. If recovered, the credential could be used to authenticate as the internal superuser to nodes in the deployment.
Severity
9 (Critical)
CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
8.8 (High)
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-11 20:21 UTC
CWE
  • CWE-757 - Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')
Assigner
mongodb CNA under the mitre root
CNA scorecard C 70/100 over 253 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
MongoDB MongoDB Server Affected: 8.3.0 , < 8.3.8 (semver)
Affected: 8.0 , < 8.0.29 (semver)
Affected: 7.0 , < 7.0.40 (semver)
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How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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