CVE-2026-82061: Database Server Use-After-Free Vulnerability

CVE-2026-82061 Overview

CVE-2026-82061 is a use-after-free vulnerability [CWE-416] in the query execution memory tracking subsystem of a database server component tracked in the MongoDB Server issue tracker as SERVER-130907. An authenticated user holding read privileges can trigger a write to freed heap memory by issuing a specific sequence of standard database commands. Successful exploitation causes the server process to crash or corrupts heap memory. No user interaction is required, and the attack is delivered over the network.

Critical Impact
An authenticated low-privilege user can crash the database server or corrupt server memory remotely, threatening integrity and availability of database workloads.

Affected Products

MongoDB Server (see MongoDB Server Issue Tracker SERVER-130907 for affected version ranges)
Deployments exposing authenticated read access to untrusted principals
Downstream services embedding the affected server component

Discovery Timeline

2026-09-08 - CVE-2026-82061 published to the National Vulnerability Database (NVD)
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-82061

Vulnerability Analysis

The vulnerability resides in the server's query execution memory tracking subsystem. During query execution, the subsystem tracks heap allocations tied to operator state. Under a specific command sequence, a tracked allocation is freed while a reference to that allocation remains reachable. A subsequent operation writes through the stale reference, producing a use-after-free condition.

The write to freed heap memory yields two primary outcomes. First, if the freed region has been recycled by the allocator, the write corrupts unrelated heap metadata or object state. Second, if the region remains uncommitted or straddles a page boundary, the process aborts. Both outcomes damage server integrity and availability without requiring elevated privileges.

An attacker needs an authenticated session with read privileges. No user interaction is needed to reach the vulnerable code path. Refer to MongoDB Server Issue Tracker SERVER-130907 for engineering details on the affected code path.

Root Cause

The root cause is improper lifetime management in the query memory tracker. The subsystem releases an allocation without invalidating outstanding references held by the execution pipeline. Reuse of the dangling reference during subsequent query state updates constitutes classic [CWE-416] Use After Free behavior.

Attack Vector

The attack vector is the network-exposed database wire protocol. An authenticated principal with read access sends a crafted sequence of standard commands that exercises the vulnerable memory tracking path. Attack complexity is low, and no user interaction is required. Public proof-of-concept code is not available at the time of publication.

No verified exploit code is available. See the MongoDB Server Issue Tracker for engineering context.

Detection Methods for CVE-2026-82061

Indicators of Compromise

Unexpected mongod process crashes, segmentation faults, or SIGABRT events in system and container logs correlated with query activity from a single authenticated user.
Repeated query command sequences from the same session immediately preceding a server restart or failover event.
Anomalous heap corruption diagnostics or tcmalloc/allocator assertions recorded in server logs.

Detection Strategies

Correlate database server crash events with the preceding command history for the initiating session to identify reproducible trigger sequences.
Alert on authenticated read-only accounts issuing atypical query patterns that repeatedly precede process termination.
Baseline normal query workload per service account and flag deviations that align with server availability events.

Monitoring Recommendations

Forward database audit logs, crash dumps, and process supervisor events into a centralized analytics platform for cross-source correlation.
Monitor replica set state changes, primary step-downs, and unplanned elections that may indicate exploitation attempts.
Track authentication events for low-privilege accounts and correlate with query error rates and process uptime.

How to Mitigate CVE-2026-82061

Immediate Actions Required

Review MongoDB Server Issue Tracker SERVER-130907 to identify fixed versions and apply the vendor patch to all affected server nodes.
Audit database roles and revoke read privileges from accounts that do not require them, minimizing the population that can reach the vulnerable code path.
Rotate credentials for read-privileged accounts that are shared across services or exposed to untrusted networks.

Patch Information

MongoDB tracks the fix under SERVER-130907. Consult the MongoDB Server Issue Tracker for the resolved version list and upgrade guidance. Apply the fixed release across all replica set members and sharded cluster components, then validate cluster health before returning nodes to production traffic.

Workarounds

Restrict network exposure of the database service to trusted application tiers using firewall rules, security groups, or private networking.
Enforce least-privilege role assignments so that only vetted service identities hold read privileges on affected clusters.
Enable process supervisor auto-restart and configure replica set failover to reduce availability impact until patches are applied.

bash

# Configuration example: restrict bind address and enforce authentication
net:
  bindIp: 127.0.0.1,10.0.0.10
  port: 27017
security:
  authorization: enabled