CVE-2026-89099 in Server
Summary
by MITRE • 09/11/2026
A race condition in the document value layer of MongoDB Server can allow concurrent server threads to operate on the same internal memory without synchronization, leading to memory corruption. An authenticated user holding ordinary read-write privileges on a database may be able to trigger this condition over the normal client protocol, resulting in server termination and potential corruption of process memory with user-influenced content. Successful use of this issue may impact the confidentiality, integrity, and availability of the affected server process.
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Analysis
by VulDB Data Team • 09/11/2026
The vulnerability described involves a critical race condition within the document value layer of MongoDB Server, specifically affecting how concurrent server threads interact with internal memory structures. This flaw arises from a lack of proper synchronization mechanisms when multiple threads attempt to access or modify shared data simultaneously. In multi-threaded environments like database servers, ensuring that only one thread can execute certain operations on shared resources at any given time is essential for maintaining system stability and data integrity. Without these safeguards, the application enters an inconsistent state where memory corruption occurs due to conflicting read-write operations. This type of flaw is commonly categorized under CWE-362, which defines race conditions involving concurrent processes or threads that can lead to unexpected behavior when execution order assumptions are violated.
From a technical perspective, this vulnerability allows authenticated users with standard read-write privileges on any database within the MongoDB instance to trigger the condition through normal client protocol interactions. The attacker does not require elevated administrative rights, making it significantly more dangerous as it lowers the barrier for exploitation. By crafting specific queries or operations that induce high concurrency and rapid state changes in document values, an adversary can force the server threads into a race scenario. This leads to memory corruption where user-influenced content overwrites critical process memory structures. Such manipulation of internal memory states is particularly severe because it bypasses typical access controls by leveraging legitimate authentication credentials while exploiting underlying architectural weaknesses rather than input validation errors alone.
The operational impact of this vulnerability extends across all three pillars of the CIA triad: confidentiality, integrity, and availability. The immediate consequence is often server termination due to segmentation faults or other fatal exceptions triggered by corrupted memory pointers. This results in a denial-of-service condition where legitimate users are unable to access data services until the service is restarted. Beyond simple downtime, the potential for arbitrary code execution exists if an attacker can precisely control the overwritten memory content. Although the description emphasizes corruption and termination, historical precedents with similar race conditions in database engines suggest that heap-based buffer overflows or use-after-free scenarios could potentially be chained to achieve remote code execution. This would compromise confidentiality by allowing unauthorized data access and integrity by enabling modification of stored records without detection.
In terms of threat modeling, this vulnerability aligns with MITRE ATT&CK techniques related to resource hijacking and privilege escalation via local exploits. Specifically, it reflects behaviors associated with exploiting software vulnerabilities for denial-of-service or initial access if combined with other flaws. The ability to crash the server process impacts availability directly, while memory corruption poses a latent risk for further exploitation steps such as shellcode injection. Organizations relying on MongoDB must recognize that even routine administrative tasks performed by low-privileged users can serve as vectors for significant system compromise when synchronization logic is flawed in core components like document handling layers.
Mitigation strategies primarily involve applying vendor-provided patches and updates immediately upon release, as these typically include fixes to the locking mechanisms or atomic operations within the affected code paths. Administrators should ensure that their MongoDB instances are running versions where this race condition has been resolved through rigorous testing of concurrent access patterns. Additionally, implementing network-level controls such as firewalls can limit exposure by restricting direct client connections to only authorized IP addresses, thereby reducing the attack surface available for triggering the vulnerability. Enabling audit logging allows security teams to monitor for unusual spikes in query concurrency or error logs indicating memory faults, providing early warning signs of attempted exploitation attempts before full system compromise occurs.