2026-06-10 1.8.3

* Fix an integer overflow when parsing maps.

2026-06-09 1.8.2

* Fix `Buffer#clear` to properly reset memory chunks before adding them back to the pool.

This could have caused data to leak across buffers when using the MessagePack::Buffer API

directly. [CVE-2026-54522].

2026-05-28 1.8.1

* Workaround rare compilation issue when `rb_hash_new_capa` isn't properly detected.

* Never pre-allocate strings larger than the buffered size.

2025-02-06 1.8.0

* Numerous small optimizations.

* Added `key_cache` option to `Unpacker`.

2024-11-11 1.7.5

* Rerelease 1.7.4 with fixed java package.

2024-11-11 1.7.4

* Fixed a potental memory leak when recursive unpacker raise.

2024-10-03 1.7.3

* Limit initial containers pre-allocation to `SHRT_MAX` (32k) entries.

2023-07-18 1.7.2:

* Fix a potential GC bug when packing data using recursive extensions and buffers containing over 512KkiB of data (See #341).

* Fix a regression where feeding an empty string to an Unpacker would be considered like the end of the buffer.

2023-05-19 1.7.1:

* Fix JRuby 9.4 compatibility.

* Fix compilation on older compilers (gcc 4.x).

* Fix an infinite recursion issue when registering a Symbol type with a `nil` packer.

2023-03-29 1.7.0:

* Fix a possible double-free issue when GC triggers inside `_msgpack_rmem_alloc2`.

* `Unpacker#feed` now always directly read in provided strings instead of copying content in its buffer.

* `Unpacker#feed` is now an alias of `Unpacker#feed_reference`.

* Implement `Factory::Pool#unpacker` and `Factory::Pool#packer` to allow for more precise serialization.

* Require Ruby 2.5+.

2023-03-03 1.6.1:

* Undefine `#clone` and `#dup` on `MessagePack::Buffer`, `MessagePack::Packer` and `MessagePack::Unpacker`.

These methods were never intended, and using them could cause leaks or crashes or worse.

* Fix a possible GC crash when GC trigger inside `MessagePack::Buffer.new` (#314).

2022-09-30 1.6.0:

* Fix a potential use-after-free bug in Buffer_free when accessing a packer or unpacker buffer.

* `old-style-definition` compilation warnings.

* Restore zero-copy buffer feed when provided a Ruby string. This was accidentally broken in 1.5.4.

* Provide implementations for `ObjectSpace.memsize`. Message pack objects now properly report their size to Ruby.

* Fix an endianess bug on Windows platform.

2022-08-23 1.5.6:

* No actual code change, just re-release the `java` version properly.

2022-08-22 1.5.5:

* Fix a segfault when GC triggers inside a recursive extension.

2022-07-25 1.5.4:

* Fix a segfault when deserializing empty symbol (`:""`).

* Improve compilation flags to not strip debug symbols.

2022-05-30 version 1.5.3:

* Fix deduplication of empty strings when using the `freeze: true` option.

* Use `rb_hash_new_capa` when available (Ruby 3.2) for improved performance when parsing large hashes.

2022-05-27 version 1.5.2:

* Fix bug about unpacking ext type objects with the recursive option

2022-04-07 version 1.5.1:

* Fix bug about packing/unpacking ext type objects with the recursive option

2022-04-06 version 1.5.0:

* Add recursive option on Factory#register_type to operate Packer/Unpacker manually

* Add oversized_integer_extension option on Factory#register_type to pack/unpack bigint using ext types

* Add Factory#pool method and Factory::Pool class to provide pooled Packer and Unpacker instances

2022-02-15 version 1.4.5:

* Fix to create UTF-8 Symbol keys when symbolize_keys: true

* Fix to assume Symbols as US-ASCII or UTF-8

* Optimize Packer/Unpacker initialization

* Optimize extension class lookup

* Rename Packer#clear as Packer#reset (#clear is still available as an alias)

2022-01-22 version 1.4.4:

* Specify the build option --platform=8 for older Java platforms

2022-01-20 version 1.4.3:

* Optimize serialization/deserialization of Symbols

* Support registering ext types for objects of subclasses of primitive types (like Hash)

* Add optimized_symbols_parsing option to Factory#register_type on MRI implementation

* Optimize to deduplicate Hash keys on JRuby

* Support JRuby 9.3 (and drop 9.1)

2021-02-01 version 1.4.2:

* Add the required Ruby version (>= 2.4) to avoid compilation errors on older Ruby runtimes

* Drop the support of old Ruby versions explicitly (1.8, 1.9, 2.0, 2.1, 2.2, 2.3)

2021-01-27 version 1.4.1:

* Bugfix about the wrong string encoding longer than 256 bytes (#200)

2021-01-27 version 1.4.0:

* Introduce the optimization to use frozen/deduped keys for map objects

* Stop releasing fat gem (pre-built binaries) for mswin32 arch environments

2020-02-05 version 1.3.3:

* Hotfix release for Windows environments: 1.3.2 missed including binaries

2020-02-04 version 1.3.2:

* Add Ruby 2.7.0 binary in gem releases for Windows

2019-08-05 version 1.3.1:

* Fix timestamp ext type bug about timestamps with seconds larger than 32bit int (after 2106-02-07 06:28:16 UTC)

2019-06-20 verison 1.3.0:

* Add timestamp ext type (id:-1) support

2019-04-19 version 1.2.10:

* Optimze MessagePack.unpack not to copy source string

2019-03-13 version 1.2.9:

* Hotfix release only for JRuby: 1.2.8-java was built incorrectly

2019-03-11 version 1.2.8:

* Fix a regression that MessagePack#unpack raises error if IO is assigned as the (only) argument

* Improve compatibility that MessagePack#pack returns nil if IO is assigned as 2nd argument

2019-03-01 version 1.2.7:

* Add Packer#write_bin and Packer#write_bin_header methods

2019-01-08 verison 1.2.6:

* Update Ruby version 2.6 dependency (especially for Windows environment)

* (version 1.2.4 and 1.2.5 were also releases for updated Ruby versions)

2018-03-02 version 1.2.3:

* Add Ruby 2.5.0 binary in gem releases for Windows

2018-01-11 version 1.2.2:

* Fix bug to occur SEGV occasionally (depends on GC timing) when exttype is used

* Fix bug to encode an ext type with wrong type id if superclass is also registered as ext type

2017-12-08 version 1.2.1:

* Hotfix release only for JRuby: 1.2.0-java was built in incorrect way

2017-12-07 version 1.2.0:

* Add MessagePack::Factory#dump and MessagePack::Factory#load as convenient methods

like MessagePack.dump and MessagePack.load

* Fix bug to accept MessagePack::Factory#register_type after #freeze

2017-02-28 version 1.1.0:

* Fix the extension type handling to accept modules in addition to classes

2017-01-24 version 1.0.3:

* Support Ruby 2.4

2016-10-17 version 1.0.2:

* Bump version up to release newer version to fix broken gem release for JRuby

2016-10-17 version 1.0.1:

* Fix a bug to crash at packer when ext type is registered for superclass of packed object

* Fix JRuby implementation about inconsistent API of Unpacker constructor

2016-07-08 version 1.0.0:

* Fix to be able to pack Symbol with ext types

* Fix for MRI 2.4 (Integer unification)

2016-05-10 version 0.7.6:

* Fix bug to raise IndexOutOfBoundsException for Bignum value with small int in JRuby

2016-04-06 version 0.7.5:

* Improved support for i386/armel/armhf environments

* Fix bug for negative ext type id and some architectures (arm*)

2016-01-08 version 0.7.4:

* Improved compatibility of Packer between CRuby and JRuby about argument IO-ish object values.

2016-01-07 version 0.7.3:

* Add Packer#write_float32 method to pack floating point numbers into FLOAT of messagepack.

2016-01-06 version 0.7.2:

* Improved compatibility of Unpacker between CRuby and JRuby to accept stream-like object

by checking respond_to(:read) in addition to class check

2015-11-20 version 0.7.1:

* Fixed bug to pack/unpack ext type objects larger than 256bytes incorrectly.

2015-10-24 version 0.7.0:

* Add extension types support.

* Fix to share almost all test cases between CRuby and JRuby implementations.

* Fixed JRuby implementation to raise UnknownExtTypeError for unregistered ext type ids

instead to generate MessagePack::ExtensionValue instances.

(Specify `allow_unknown_ext: true` as unpacker option for v0.6.x behavior.)

2015-07-22 version 0.6.2:

* Fix release workflow: Ruby 2.1 and 2.2 are supported for Windows (2.0 is omitted)

* Fix to encode symbols along its encoding

* Fix segmentation fault in minor case

2015-07-01 version 0.6.1:

* Added :compatibility_mode option to Packer#initialize. Default is false. If it

is set to true, str8 format and bin format family will not be used.

2015-05-26 version 0.6.0:

* Added support for Binary types

* Fixed to encode/decode between Binary types and ASCII-8BIT Ruby String objects

2015-05-21 version 0.5.12:

* Added support for JRuby 9K.

* Added a benchmarking suite.

* Fixed a bug in the handling of options given to MessagePack.unpack in JRuby.

2015-02-04 version 0.5.11:

* Fixed Encoding::CompatibilityError error when serializing a long string

longer than write_reference_threshold (5KB by default) and whose encoding

is not ASCII-8BIT.

* Fix read_(map|array)_header (@funny-falcon++).

* Internally, rename msgpack_unpacker_{init,reset,destroy} functions

so that we can load msgpack-c in the same process (@miihael++)

2015-01-09 version 0.5.10:

* Merged msgpack-jruby by @iconara. JRuby can run `require 'msgpack'` to use

msgpack-jruby.

2014-10-05 version 0.5.9:

* Fixed Unpacker#read_map_header and #read_array_header

* Added support for Symbol GC added since MRI 2.2.0

2013-12-14 version 0.5.8:

* Fixed compatibility with Ruby 2.1.0

* Added :symbolize_keys option to MessagePack.load and Unpacker#initialize

2013-10-12 version 0.5.7:

* Added deserialization support for the new MessagePack spec

2013-09-23 version 0.5.6:

* Fixed "can't modify frozen String" exception in Unpacker with ruby 2.1.0-dev

* Getting work with Ruby v2.0 on Windows (Thank you @thegreendroid)

* Fixed EOFError handling in Unpacker

2013-05-12 version 0.5.5:

* Fixed SEGV problem in to_msgpack

* Fixed a possible race condition in MessagePack.load when it loads data from IO

* mingw32 package includes binary for ruby-2.0.0

2013-03-15 version 0.5.4:

* Added missing MessagePack::Unpacker#reset method

2013-02-14 version 0.5.3:

* Fixed segfault problem on Buffer#clear (reuse rmem internal fragment optimization)

* Fixed segfault problem on Buffer (rmem free code)

2013-02-07 version 0.5.2:

* Fixed invalid pack/unpack on 32bit architecture such as Win32

* Disable rmem on Rubinius because rmem is not thread safe

2012-12-23 version 0.5.1:

* Fixed compile error with Rubinius 2.0.0-dev

* Optimized msgpack_packer_write_hash for Rubinius

2012-12-20 version 0.5.0:

* Rewrote all code and improved performance significantly

* Added MessagePack::Buffer class

* Added MessagePack::Packer class

* Added Packer#buffer and Unpacker#buffer accessors which return MessagePack::Buffer

* Added Packer#write_{array,map}_header and Unpacker#read_{array,map}_header methods

* Added Packer#write_nil and Unpacker#skip_nil methods

* Added Packer#write -> #pack alias and Unpacker#read method

* Added exception classes - UnpackError, MalformedFormatError, StackError and TypeError

* Added MessagePack.dup -> .pack and MessagePack.load -> .unpack aliases

* Added Packer#empty?, #size and #clear methods

* Added Packer#write_to(io) method to flush serialized data to IO efficiently

* Added Unpacker#skip method to skip an object efficiently

* Removed obsoleted Unpacker#fill, #execute, #execute_limit, #finished? and #data methods

* Removed obsoleted Unapcker#stream and #stream= methods. Use unpacker.buffer.io instead

2012-05-05 version 0.4.7:

* Fixed serialization of double values on ARM OABI architectures

* Fixed byteorder problem on big-endian platforms

* Don't use MRI internals in the Ruby extension for Rubinius

* Detect whether st.h is present and don't use RUBY_VM as the condition for

Rubinius

2011-08-08 version 0.4.6:

* Fixed compile error problem on Mac OS X Lion

2011-05-09 version 0.4.5:

* Improves compatibility with JRuby

2010-11-28 version 0.4.4:

* Adds Unpacker#feed_each method

* Improves compatibility with Rubinius

* Improves compatibility with ruby-1.8.5

* Encodings of String instances to UTF-8 on Ruby 1.9

2010-06-29 version 0.4.3:

* Adds MessagePack::VERSION constant

* Fixes SEGV problem caused by GC bug at MessagePack_Unpacker_mark