MongoDBCVE-2026-18691
An issue in MongoDB Server's intra-cluster connection setup
Critical9.0CVE-2026-18691 · Published Aug 11, 2026 · updated Sep 16, 2026
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.
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| MongoDB Server Product | >= 8.3.0, < 8.3.8 | 8.3.8 |
| >= 8.0, < 8.0.29 | 8.0.29 | |
| >= 7.0, < 7.0.40 | 7.0.40 |
Details and references
- CVSS 4.0
- 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
- Severity from
- the vendor (its own CVE record or advisory)
- Weakness
- CWE-757
More MongoDB advisories
All MongoDB| Date | Advisory | Severity | Fixed in |
|---|---|---|---|
| Aug 11 | Cleartext Storage of Sensitive Information in MongoDB Driver Logging During Client Initialization | Medium6.5 | 5.9.2+1 more |
| Aug 11 | MongoDB Server: improper authorization | High7.2 | 8.3.8+2 more |
| Aug 11 | MongoDB Server: use after free | High7.1 | 8.3.8+1 more |
| Aug 11 | MongoDB Server: missing authorization | High7.1 | 8.3.8 |
| Aug 11 | MongoDB Server: untrusted input in a security decision | High7.1 | 8.3.8+2 more |
| Aug 11 | MongoDB Server: use after free | High7.5 | 8.3.8 |