Mongodb Mongodb
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 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.
What this means for your business
- It affects Mongodb. It matters if your company, or a supplier that handles your data, runs it.
- An attacker can use it from inside the same network, without a login, and without anyone at your company clicking anything.
- FIRST's prediction model gives it a 0.2% chance of attack attempts being seen in the next 30 days, ranking above 14% of all known flaws.
What to do
- 1Check whether your company or your suppliers run Mongodb, and which version. The affected versions are listed further down this page.
- 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.
Not sure if your company is exposed?
Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.
Scoring
- CVSS
- 8.8 (v3.1)
- Vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- CVSS v4
- 9.0
- Weakness
- CWE-757
- Assigned by
- cna@mongodb.com
Dates
- Published
- 2026-08-11
- Last modified
- 2026-09-16
- Sources
- NVD
Affected products
- Mongodb Mongodb7.0.0 - 7.0.40, 8.0.0 - 8.0.29, 8.2.0 - 8.2.12, 8.3.0 - 8.3.8, 9.0.0, 9.1.0
As listed in the NVD configuration data. Not a statement about your estate.