CVE-2026-84962

In MongoDB 2.6, when using 2.4-style users, remote attackers can cause a denial of service by leveraging in-memory database representation when authenticating against a non-existent database.

MongoDB versions 3.4.x before 3.4.10 and 3.5.x-development have a disabled-by-default configuration setting, networkMessageCompressors, which when enabled can be exploited by a malicious attacker to deny service or modify memory.

An uncontrolled resource consumption weakness exists in the request-handling path of the MongoDB sharded-cluster router process. A client that has network access to a router port and has not authenticated can supply connection-monitoring parameters that cause the server to expend CPU resources without any rate limiting, degrading or denying service to legitimate clients. No authentication, elevated privileges, or user interaction is required. Only availability is affected; data confidentiality and integrity are not impacted.

A vulnerability in MongoDB's JSON Schema validation error generation code allows an authenticated user with readWrite privileges to crash the mongod server. When a BSON document containing an array with a malformed numeric field name fails a $jsonSchema items type constraint, the error generation path performs unsafe numeric conversion on the user-controlled field name without proper exception handling, resulting in an uncaught exception that terminates the server process. This is possible because incoming wire protocol BSON validation does not enforce that array element field names are valid, in-range numeric indices.

A security issue was discovered in MongoDB where an authenticated user with readWrite privileges could crash the mongod server process. By specifying a custom WiredTiger storage configuration option with an incompatible value during collection creation, a user could cause a type confusion in the storage engine layer. When documents were subsequently read from the misconfigured collection, the resulting mismatch in expected data format led to corrupted memory interpretation and a server crash. The crafted collection configuration persists across restarts, requiring manual operator intervention to remediate.

A race condition in MongoDB server's text index query parsing can cause a heap use-after-free read when handling upsert retry paths. Under certain concurrent index lifecycle operations, a raw pointer to internal text index metadata may be dereferenced after the underlying structures have been freed, leading to a server crash. An authenticated user with readWrite privileges can trigger this condition through specific concurrent text-search and index management operations, resulting in denial of service for all connected clients.

A security issue exists in MongoDB's 2dsphere index key generation that can cause a server crash due to a null pointer dereference. When a specially crafted GeoJSON document is inserted into a collection with a 2dsphere index, an inconsistency in geometry parsing can leave an internal object in an invalid, partially initialized state. During subsequent index key generation, access to this improperly initialized object results in a null pointer dereference that terminates the mongod process. An authenticated user with write access can use this to cause a denial of service.

A security issue exists in MongoDB server's JSON Pointer parser used during $jsonSchema query filter processing. When a find command includes a specially crafted $jsonSchema filter field, the parser processes the input without enforcing adequate limits on iteration count or total allocation size, resulting in significant memory amplification. Under concurrent request load, the cumulative memory consumption can exhaust available heap memory, causing the server's out-of-memory handler to terminate the mongod process and deny service to all connected clients.

The $regexFindAll expression can be used by an authenticated user who can run aggregation pipeline stages to crash a MongoDB server (mongod). Under certain specific conditions the regex match can start in the middle of a multi-code-unit character, triggering an assertion during query execution.

During query planning in MongoDB, when reading the sort pattern in raw BSONObj form, some places do not explicitly handle the meta expression case. This may lead to incorrect transformations and invariant failure.