Loading vulnerability…
CVE-2026-18691 is an authentication mechanism downgrade vulnerability in MongoDB Server affecting intra-cluster connection setup between replica set members. A party with suitable adjacent network access can influence which authentication mechanism is negotiated when one replica set member connects to another. Under certain conditions, this can cause the cluster’s shared internal credential to be transmitted in a less-protected form, creating an opportunity for credential recovery. If the shared internal credential is recovered, it can be used to authenticate to deployment nodes as the internal superuser. Reported affected versions are MongoDB Server 7.0 before 7.0.40, 8.0 before 8.0.29, and 8.3.0 before 8.3.8.
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
If you can’t patch tonight, do this now.
Patch, then assume compromise.
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
5 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A specific vulnerability identified as CVE-2026-18691 affecting MongoDB packages on Ubuntu Linux LTS releases, referenced in an unpatched Nessus plugin entry.
A vulnerability in MongoDB Server intra-cluster connection setup that may allow an adjacent-network attacker to influence authentication mechanism selection and recover the cluster's shared internal credential, potentially enabling authentication as the internal superuser.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.