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Vulnerabilities

Vulnerability · CVE-2026-18691

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 o…

Published Aug 11, 2026 · catalog updated Oct 23, 2026 · the affected product

Last checked Nov 1, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-18691. EPSS is 0.36%. Act only if a listed version of the affected product is installed.

Gaps on this record

  • No plain product name is stored. The page cannot tell you which product to check.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Critical9.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.36%
Remediation
Version ranges on file
Affected products
cpe mongodb/mongodb

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe mongodb/mongodb9.0.0
  • cpe mongodb/mongodb< 7.0.40
  • cpe mongodb/mongodb< 8.0.29
  • cpe mongodb/mongodb< 8.3.8
  • cpe mongodb/mongodb>= 8.2.0, <= 8.2.12

How to fix CVE-2026-18691

  • Upgrade

    CVE-2026-18691 lists a fix boundary at 7.0.40. Compare the installed build with that boundary before you change production.

  • Version check

    Affected < 7.0.40

  • Advisory

    Open the inventory_high record and follow its fix.

  • Official advisories

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-18691. EPSS is 0.36%. Act only if a listed version of the affected product is installed.

Which versions are affected?

Compare what you have installed with 9.0.0, < 7.0.40, < 8.0.29, < 8.3.8, >= 8.2.0, <= 8.2.12. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-757. EPSS 0.36%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

MongoDB security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Aug 11, 2026 · Monitored products — high

    Detected

    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 recov

  2. Oct 23, 2026 · Monitored products — high

    Updated

    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 recov

Sources

  • Monitored products — highVendor advisoryCVE-2026-18691

    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 recov

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 1, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Monitored products — highNov 1, 2026