CVE-2026-18691 json
Improper Authentication in MongoDB Intra-Cluster Connections Allows Credential Exposure
published 2026-08-11 2 mo ago modified 2026-10-23 16 d ago also BIT-mongodb-2026-18691 , EUVD-2026-56921
- cvss
- 8.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 29%
- public exploits
- 0
- none known
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.
Patch / fix
- bitnami mongodb 7.0.40, 8.0.29, 8.3.8, 9.0.2
- MongoDB MongoDB Server 7.0.40, 8.0.29, 8.3.8
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 2 mo ago
Exploit prediction
0.36% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 9.0 | 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 |
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CNA | 4.0 | 9.0 | 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/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 |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| bitnami | mongodb | >=7.0.0, <7.0.40 >=8.0.0, <8.0.29 >=8.2.0, <8.3.8 >=9.0.0, <9.0.2 |
7.0.40 8.0.29 8.3.8 9.0.2 |
Affected products
- MongoDB MongoDB Server
Classification
- Weakness
-
- CWE-757 Selection of Less-Secure Algorithm During Negotiation
- Technology feeds
References
-
jira.mongodb.org
/browse/SERVER-130264
vendor-advisory, issue-tracking, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-18691
web
Sources
- CVE List CVE-2026-18691
- NVD CVE-2026-18691
- OSV BIT-mongodb-2026-18691
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