MongoDB Server Pre-Authentication Vulnerability Let Attackers Trigger DoS Condition

A critical pre-authentication denial of service vulnerability was identified as CVE-2025-6709, affecting multiple versions of MongoDB Server across its 6.0, 7.0, and 8.0 release branches. 

Summary
1. MongoDB CVE-2025-6709 allows unauthenticated attackers to crash servers (CVSS 7.5).
2. Malicious JSON payloads with crafted date values sent via MongoDB shell exploit OIDC authentication flaws.
3. MongoDB Server v6.0 (prior-6.0.21), v7.0 (prior-7.0.17), and v8.0 (prior-8.0.5).
4. Update immediately to patched versions or disable OIDC authentication as temporary mitigation

The vulnerability stems from improper input validation in the server’s OpenID Connect (OIDC) authentication mechanism, allowing attackers to crash database instances without requiring authentication credentials. 

With a CVSS score of 7.5, this high-severity flaw poses significant risks to organizations running vulnerable MongoDB deployments in production environments.

MongoDB DoS Vulnerability 

The vulnerability categorized under CWE-20 (Improper Input Validation), exploits flawed handling of specific date values within JSON payloads during OIDC authentication processes. 

Attackers can leverage the MongoDB shell (mongo) to transmit specially crafted malicious JSON data that triggers an invariant failure condition, ultimately leading to complete server crashes. 

The attack mechanism bypasses traditional authentication requirements, making it particularly dangerous as it enables unauthenticated remote attackers to disrupt database operations.

The technical root cause involves inadequate sanitization and validation of date-formatted input data within the OIDC authentication pipeline. 

When the MongoDB server processes these malformed date values, the parsing logic encounters unexpected data structures that violate internal assumptions, causing the server process to terminate unexpectedly. 

This represents a classic input validation vulnerability where insufficient boundary checking and data type validation create exploitable conditions.

The vulnerability impacts three major MongoDB Server release branches with varying severity levels. 

MongoDB Server v7.0 versions prior to 7.0.17 and v8.0 versions prior to 8.0.5 are susceptible to pre-authentication exploitation, allowing completely unauthenticated attackers to trigger denial of service conditions remotely. 

MongoDB Server v6.0 versions prior to 6.0.21 also contain the vulnerability, though exploitation requires successful authentication, reducing the immediate threat surface but still presenting risks from authenticated users.

Organizations running these vulnerable versions face potential service disruptions, especially in high-availability environments where database downtime directly impacts business operations. 

The network-based attack vector (AV:N) combined with low attack complexity (AC:L) makes this vulnerability particularly concerning for internet-facing MongoDB deployments or those accessible through compromised network segments.

Mitigations

According to the advisory, Security teams should prioritize immediate patching to the latest stable releases: MongoDB Server 6.0.21, 7.0.17, or 8.0.5, depending on their current deployment version. 

Organizations unable to implement immediate patches should consider implementing network-level access controls, disabling OIDC authentication temporarily if not critical to operations, or deploying web application firewalls capable of filtering malicious JSON payloads.

The pre-authentication nature of this vulnerability makes it an attractive target for threat actors seeking to disrupt database services without sophisticated attack techniques. 

Database administrators should monitor for unusual connection patterns, implement comprehensive logging around OIDC authentication attempts, and establish incident response procedures for rapid service restoration following potential exploitation attempts.

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