Fixed

• Use exact match for file ID in GridFS methods CVE-2026-88034

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Fixed

• Validate key lengths. CVE-2026-84970
• Validate before casting length in from_json. CVE-2026-84966

See the full list of changes in Jira.

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Signature Verification

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Fixed

• Validate database and collection name arguments against "." and NUL bytes. (CVE-2026-81522)

See the full list of changes in Jira.

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Signature Verification

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Removed

• Support for Visual Studio 2015 (EOL since Oct 2025). Use Visual Studio 2017 15.9 (MSVC 19.16.27023) or newer.

Added

• Support appending client handshake metadata after initialization and per-client/pool. This is useful for projects wrapping the C++ driver to self-identify.

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Signature Verification

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Changed

• Bump the minimum required C Driver version to 2.3.3.

See the full list of changes in Jira.

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Signature Verification

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Fixed

• Include of v1/text_options.hpp (normal header) by options/text-fwd.hpp (forward header).
• Include of v_noabi macro guard headers by text_options.hpp (v1).

Deprecated

• Support for MongoDB Server 4.2.
  • See: MongoDB Software Lifecycle Schedules.

Changed

• Stable ABI (v1) is now officially supported for both bsoncxx and mongocxx libraries.
• The soversion for both bsoncxx and mongocxx libraries is now set to 1.
• Library filenames now include the ABI version number, e.g. libbsoncxx1.so.4.4.0.
• pkg-config config filenames now include the ABI version number, e.g. libbsoncxx1.pc.
• CMake package config filenames now use camelCase, e.g. bsoncxxConfig.cmake.
• Bump the minimum required C Driver version to 2.3.1.

Added

• Support for the "readConcern" option field to "delete", "insert", "replace", "bulkWrite", "findOneAnd*", "count", and "distinct" operations.
• Support for MONGODB-OIDC authMechanism.
• Support for client bulk write API (mongocxx::client_bulk_write).
  • Unlike collection bulk write (mongocxx::bulk_write), client bulk write supports writes across more than one collection and can group inserts, updates, and deletes in the same network payload.
  • Requires MongoDB Server 8.0 or newer.
  • See:
    • Bulk Write Operations (MongoDB Manual)
    • bulkWrite (MongoDB Manual)

See the full list of changes in Jira.

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Signature Verification

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Fixed

• Do not set upsert: true in "findOneAnd*" operations when the option is explicitly set to false (regression in 4.2.0).

See the full list of changes in Jira.

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Signature Verification

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Fixed

• Added missing subscript operators for class types declared in bsoncxx::vector::iterators.

Deprecated

• Support for Visual Studio 2015 (EOL since Oct 2025). Use Visual Studio 2017 or newer.

Changed

• Bump the minimum required C Driver version to 2.3.0.

Added

• Added support for MongoDB's Intelligent Workload Management (IWM) and ingress connection rate limiting features. The driver now gracefully handles write-blocking scenarios and optimizes connection establishment during high-load conditions to maintain application availability.
  • Supported on all commands.
  • Custom application retry logic may need to be adjusted to avoid retrying too long.
  • Upgrade is recommended to avoid impacts of server changes related to overload errors.
    • If not upgrading, custom application retry logic may need to be adjusted to handle higher rates of overload errors.
  • Add URI option maxAdaptiveRetries to configure the maximum number of retries for operations that fail with a SystemOverloadedError (default: 2).
  • Add URI option enableOverloadRetargeting to control whether retries of SystemOverloadedError will attempt to use a different server (default: false).
  • These features will be functional with MongoDB Atlas Server Version 9.0 and above.
• Added support for the "readConcern" option field to "find" and "update" operations.

See the full list of changes in Jira.

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Signature Verification

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Added

• Experimental support for stable ABI interfaces under the v1 namespace for both bsoncxx and mongocxx libraries.
• To support incremental migration, the following entities are defined as equivalent to their renamed counterparts.
  • bsoncxx::types::id: equivalent to bsoncxx::type.
  • bsoncxx::types::binary_subtype: equivalent to bsoncxx::binary_sub_type.
  • bsoncxx::types::view: equivalent to bsoncxx::types::bson_value::view.
  • bsoncxx::types::value: equivalent to bsoncxx::types::bson_value::value.
  • type_view() in bsoncxx::document::element and bsoncxx::array::element: equivalent to get_value().
  • type_value() in bsoncxx::document::element and bsoncxx::array::element: equivalent to get_owning_value().
• Experimental support for In-Use Encryption Text Indexes (mongocxx::v1::text_options).
• Change stream helpers for convenient iteration (mongocxx::v1::change_stream::next and mongocxx::v1::change_stream::try_next).

Changed

• For consistency with the library and package filenames of MongoDB C Driver 2.0.0 and newer:
  • CMake package config files now use the <name>Config.cmake and <name>ConfigVersion.cmake pattern. (Old: <name>-config.cmake and <name>-config-version.cmake)
• CMake 3.16.0 or newer is required when ENABLE_TESTS=ON for compatibility with the updated Catch2 library version (3.7.0 -> 3.8.1).
• Minimum supported compiler versions to build from source are updated to the following:
  • GCC 8.1 (from GCC 4.8.2).
    • Users on RHEL 7 may consult Red Hat's "Hello World - installing GCC on RHEL 7" or "How to install GCC 8 and Clang/LLVM 6 on Red Hat Enterprise Linux 7" for instructions on how to obtain GCC 8 or newer.
  • Clang 3.8 (from Clang 3.5).
  • Apple Clang 13.1 with Xcode 13.4.1 (from Apple Clang 5.1 with Xcode 5.1).
  • MSVC 19.0.24210 with Visual Studio 2015 Update 3 (from MSVC 19.0.23506 with Visual Studio 2015 Update 1).
• mongocxx::v_noabi::instance::~instance() no longer skips calling mongoc_cleanup() when compiled with ASAN enabled.
  • See google/sanitizers#89 for context.
• Bump the minimum required C Driver version to 2.2.3.

Deprecated

• mongocxx::v_noabi::instance::current() is "for internal use only". The instance constructor(s) should be used instead.
  • Creating the instance object in the scope of main(), or in an appropriate (non-global) scope such that its (non-static) lifetime is valid for the duration of all other mongocxx library operations, is recommended over the following workarounds.
  • If there is only one call to current() present within an application, it may be replaced with a static local variable:

    // Before:
    mongocxx::instance::current();
    
    // After:
    static mongocxx::instance instance; // Only ONE instance object!

  • If there are multiple calls to current() present within an application, they may be replaced with a call to a user-defined function containing the static local variable:

    mongocxx::instance& mongocxx_instance() {
      static mongocxx::instance instance; // Only ONE instance object!
      return instance;
    }

• These following entities will be renamed (and removed) in an upcoming major release. To support incremental migration, both old and new names are still provided.
  • bsoncxx::type -> bsoncxx::types::id.
  • bsoncxx::binary_sub_type -> bsoncxx::types::binary_subtype.
  • bsoncxx::types::bson_value::view -> bsoncxx::types::view
  • bsoncxx::types::bson_value::value -> bsoncxx::types::value
  • get_value() -> type_view() in bsoncxx::document::element and bsoncxx::array::element.
  • get_owning_value() -> type_value() in bsoncxx::document::element and bsoncxx::array::element.

Removed

• Support for MongoDB Server 4.2.
  • See: MongoDB Software Lifecycle Schedules.
  • See: MongoDB C Driver 2.1.0 Release Notes.
• Support for macOS 11 and macOS 12 (deprecated in 4.1.0).

Fixed

• Do not throw when comparing mongocxx::result::insert_many with non-ObjectID IDs.

See the full list of changes in Jira.

Feedback

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Signature Verification

Release artifacts may be verified by using the accompanying detached signature (.asc) and the cpp-driver public key obtained from https://pgp.mongodb.com.

Changed

• Bump the auto-downloaded C Driver version to 2.1.2.

See the full list of changes in Jira.

Feedback

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Signature Verification

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