CVE-2026-96747 in Python Driver
Summary
by MITRE • 09/24/2026
The client-side field level encryption support in the MongoDB Python Driver can treat a key management endpoint value ending in ".sock" as a local Unix domain socket path rather than a remote host. A user with write access to the encryption key metadata stored in the database can cause an application using the driver to open connections to local sockets on the application host. Data sent over these connections is limited to the start of a TLS handshake, so no chosen content is transmitted.
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Analysis
by VulDB Data Team • 09/24/2026
The MongoDB Python Driver contains a client-side field-level encryption implementation that exhibits a path resolution vulnerability when handling key management endpoint configurations. This flaw arises from an insufficient validation mechanism within the driver's network connection logic, specifically regarding how it interprets string values designated as hostnames or endpoints for external Key Management Services (KMS). When a configuration value ends with the suffix ".sock", the driver incorrectly classifies this identifier not as a remote hostname but as a local Unix domain socket path. This misclassification triggers an immediate attempt to establish a connection via the local file system rather than over the network, bypassing standard DNS resolution and remote host verification procedures that would normally apply to external endpoints.
The operational impact of this vulnerability is significant for applications relying on MongoDB's client-side field-level encryption feature. An attacker who possesses write access to the metadata stored within the database can manipulate the configuration parameters associated with encryption keys. By injecting a value ending in ".sock" into these metadata fields, the attacker forces the application process running the Python driver to initiate connections to arbitrary local Unix sockets on the host machine where the application is deployed. This capability effectively allows an unprivileged or compromised user within the database context to influence network behavior at the operating system level, potentially leading to unauthorized access to local services that expose sensitive data through their socket interfaces.
From a technical perspective, this issue represents a classic case of path traversal and injection via configuration metadata. The vulnerability aligns with CWE-20 Improper Input Validation, as the driver fails to adequately sanitize or validate the format of the endpoint string before attempting network operations. Furthermore, it relates to CWE-94 Improper Control of Generation of Code (Code Injection) in a broader sense, where user-controlled input dictates system behavior outside its intended scope. In terms of attack vectors, this scenario maps to ATT&CK technique T1053 Scheduled Task/Job, specifically the aspect of local execution via configuration manipulation, although it is more accurately described as an abuse of trust relationships between application components and operating system resources. The attacker leverages their database privileges to escalate influence into the host's network stack without requiring direct shell access or binary exploitation.
The severity of this vulnerability is somewhat mitigated by technical limitations inherent in how MongoDB handles these connections. Data transmitted over the resulting local socket connection is strictly limited to the initial bytes required for a TLS handshake initiation. The driver does not proceed to send full application payloads, certificates, or arbitrary data content beyond this handshake start sequence. Consequently, while an attacker can force the opening of sockets and potentially trigger side-channel effects or service availability issues by exhausting file descriptors or triggering errors in local services listening on those sockets, they cannot directly exfiltrate large volumes of data through this specific channel. However, the ability to probe local socket existence or cause denial-of-service conditions against critical infrastructure components remains a serious concern for high-security environments.
To mitigate this risk, organizations should immediately apply patches provided by MongoDB that address the input validation logic in the Python driver's encryption module. Until patching is feasible, administrators must enforce strict access controls on database collections storing key management metadata to prevent unauthorized users from modifying endpoint configurations. Additionally, implementing network segmentation and restricting local socket permissions can limit the blast radius of such an attack. Security teams should also monitor for unusual patterns involving Unix domain socket connections initiated by application processes that are not expected to communicate locally with KMS providers. Regular audits of database privileges ensure that only trusted service accounts retain write access to encryption key metadata, thereby reducing the likelihood of exploitation through compromised user credentials or SQL injection vulnerabilities in upstream applications.