CVE-2026-18709 Missing Authorization in MongoDB Sharded Transaction Commit/Abort Handling Leads to Cross-Shard Data Inconsistency
An authenticated user can bypass transaction coordination to cause cross-shard data inconsistency and atomicity violations in MongoDB clusters.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-18709?
CVE-2026-18709 is a medium-severity missing authorization vulnerability in Mongodb Mongodb, published on 11 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
An issue in MongoDB Server could allow an authenticated user with direct network access to a shard to improperly commit or abort an in-progress prepared transaction, bypassing the intended transaction coordination process. This could result in cross-shard data inconsistency, cluster clock corruption, and violation of transaction atomicity guarantees.
Weakness: CWE-862
Which versions are affected by CVE-2026-18709?
1 open source package ship an affected version, including mongodb. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
mongodb Bitnami | From 7.0.0 | 7.0.40, 8.0.29, 8.3.8, 9.0.2 |
Products include Mongodb Mongodb.
How do I fix CVE-2026-18709?
Upgrade mongodb to a fixed version for your release line: 7.0.40, 8.0.29, 8.3.8 or 9.0.2.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-18709 being exploited?
There is no known exploitation of CVE-2026-18709 in the wild and no public exploit code.
Other vulnerabilities in Mongodb Mongodb
- CVE-2025-14847 MongoDB and MongoDB Server Improper Handling of Length Parameter Inconsistency
- CVE-2026-82067 Auth bypass in MongoDB Server
- CVE-2026-13072 MongoDB Improper Input Validation in Compute Mode External Data Processing Leading to Memory Corruption
- CVE-2017-15535 Denial of service in n/a
- CVE-2026-18691 Improper Authentication in MongoDB Intra-Cluster Connections Allows Credential Exposure
Sources
Also known as BIT-mongodb-2026-18709, GHSA-g2m8-vcxw-5h4c, MINI-fc2g-qqgf-m522, MINI-hp64-2v88-pj5p, MINI-m2c3-x8gm-xq7c, MINI-vfwg-34c8-q4pp and 1 more.