CVE-2026-82056 Overview
CVE-2026-82056 is a race condition in MongoDB server that leads to a heap use-after-free read [CWE-416] during text index query parsing. The flaw is triggered on upsert retry paths when concurrent text-search operations run alongside index lifecycle operations. A raw pointer to internal text index metadata may be dereferenced after the underlying structures have been freed, causing the server process to crash. Exploitation requires an authenticated account with readWrite privileges. A successful trigger produces denial of service for every client connected to the affected server instance.
Critical Impact
An authenticated user with readWrite privileges can crash the MongoDB server by racing text-search queries against text index management operations, disrupting all connected clients.
Affected Products
- MongoDB Server (see MongoDB JIRA Issue SERVER-130306 for affected versions)
- Deployments using text indexes with concurrent index lifecycle operations
- Multi-tenant MongoDB clusters where authenticated users hold readWrite privileges
Discovery Timeline
- 2026-09-08 - CVE-2026-82056 published to the National Vulnerability Database (NVD)
- 2026-09-08 - Last updated in NVD database
Technical Details for CVE-2026-82056
Vulnerability Analysis
The defect resides in MongoDB server's text index query parsing logic. When the server processes an upsert that must be retried, the retry path reuses a raw pointer to text index metadata. If a concurrent index lifecycle operation (creation, drop, or rebuild) frees that metadata between the initial parse and the retry, the retry path reads freed memory. The result is a heap use-after-free read that terminates the server process. Because the crash is deterministic once the race window is hit, repeated triggering sustains denial of service against the database tier.
Root Cause
The root cause is unsynchronized access to internal text index metadata across the upsert retry lifecycle. The parser holds a non-owning pointer whose lifetime is not tied to the referenced structure. Concurrent index management operations invalidate that structure without notifying holders of the raw pointer. This ownership and synchronization gap is classified under [CWE-416] Use After Free.
Attack Vector
Exploitation is network-reachable but requires an authenticated session with readWrite privileges on a database that uses a text index. The attacker issues text-search queries that follow the upsert retry path while simultaneously issuing text index management commands. Timing is important; the CVSS 4.0 vector AV:N/AC:H/AT:P/PR:L reflects both the required race condition and the low privilege prerequisite. Impact is limited to availability (VA:H); confidentiality and integrity are not affected.
No verified proof-of-concept code is publicly available. See MongoDB JIRA Issue SERVER-130306 for vendor technical details.
Detection Methods for CVE-2026-82056
Indicators of Compromise
- Unexpected mongod process crashes with stack traces referencing text index parsing or FTS (full-text search) components.
- Sudden loss of all client connections coincident with text-search workloads against a database containing text indexes.
- Concurrent audit log entries showing createIndex, dropIndex, or collMod on a text-indexed collection alongside find or update operations issuing $text queries.
Detection Strategies
- Correlate mongod crash events with the immediately preceding query and index-management commands in the MongoDB audit log.
- Alert on any authenticated user issuing repeated text index lifecycle operations against production collections.
- Inspect crash dumps for use-after-free signatures in text index query parsing code paths.
Monitoring Recommendations
- Enable MongoDB auditing for authCheck, createIndex, dropIndex, and command execution against text-indexed collections.
- Forward mongod logs and crash telemetry to a centralized analytics platform such as Singularity Data Lake for correlation across the database tier.
- Baseline normal text-search query volume and alert on bursts of $text queries interleaved with index management commands.
How to Mitigate CVE-2026-82056
Immediate Actions Required
- Review MongoDB JIRA Issue SERVER-130306 and apply the fixed MongoDB server release for your deployment channel.
- Audit which application accounts hold readWrite on databases containing text indexes and remove privileges that are not required.
- Restrict who can execute text index lifecycle operations (createIndex, dropIndex) in production environments.
Patch Information
MongoDB tracks the fix under SERVER-130306. Consult MongoDB JIRA Issue SERVER-130306 for fixed version numbers across the maintained server release trains and apply the corresponding upgrade to every replica set member and shard.
Workarounds
- Freeze text index lifecycle operations during production query workloads until the patch is applied.
- Isolate text-search workloads on dedicated database instances so that a crash does not disrupt unrelated applications.
- Enforce network-level access controls that restrict which service accounts can reach mongod on the wire protocol port.
# Example: revoke readWrite on a database containing text indexes
mongosh --eval 'db.getSiblingDB("admin").revokeRolesFromUser("app_user", [ { role: "readWrite", db: "search_db" } ])'
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
