当初は、2018/4/27を予定していたYocto2.5(Sumo)ですが、2018/5/11(PDT14:22:35）にリリースのアナウンスがありました。
リリースの遅れは、主としてFedora28に於いて、glibcからlibcryptを分離しlibxcryptに移行した点への対応の完了後の2018/4/23時点
のものでQAサイクルに移行したためです。

リリースアナウンスは以下のURLのメーリングリストの投稿をご覧ください。
https://lists.yoctoproject.org/pipermail/yocto-announce/2018-May/000136....

旧来のバージョンとの相違については、リファレンスマニュアルのmigration informationをご覧ください。
https://www.yoctoproject.org/docs/2.5/ref-manual/ref-manual.html#moving-...

リリースアナウンスや、migration informationに記載されていない変更点として、2.3/2.4でrpm形式のパッケージを使用した場合に
発生していた、package-indexでrepodataがアーキテクチャディレクトリ以下に生成されない不具合が解消されています。

新機能・機能拡張/セキュリティFix/Updates以下のとおりです。

-----------------------------------
New Features / Enhancements
-----------------------------------

* Linux kernel 4.15/4.14/4.12, gcc 7.3, glibc 2.27 and ~240 other recipe upgrades
* Simplified enabling binary reproducible builds (reproducible_build and reproducible_build_simple classes)
* Support for installing multiple kernels at runtime and selecting between them
* Support for the Meson build system (imported from meta-oe)
* Reworked EFI boot support
* Added support to IMAGE_FSTYPES for F2FS flash filesystem generation
* A shared state mirror is now being published on yoctoproject.org in order to accelerate builds where compatible. You will need to configure the build system to point to these - details in the auto-generated local.conf (or meta-poky/local.conf.sample).
* Specific architecture support:
- Added support for RISC-V architecture (riscv32 and riscv64)
- Added Xilinx MicroBlaze architecture support
- Added support for ARM64 ILP32
- Added new tune-i686.inc for better support of 686-class CPUs
- Added support for Intel CoffeeLake-S within linux-yocto and xf86-video-intel
- Added support for stratix10 SoC development board within linux-yocto
- systemtap can now also be built for MIPS and MicroBlaze
* wic image creator improvements:
- Introduced --fsuuid option and have --use-uuid make use of UUID too
- Updated canned-wks for systemd to use file system UUID everywhere
- Added --part-name option for naming GPT partitions
- Added a do_post_partition hook for plugins to post-process a partition (useful for e.g. package signing)
- Added a template wks file to make use of exclude-path functionality (useful for e.g. splitting a single image into multiple partitions)
- wic can now be used from within in the Extensible SDK (eSDK)
* bitbake-layers improvements:
- add-layer/remove-layer: added support for adding and removing multiple layers at once
- show-recipes/show-appends: support specifying more than one recipe
* devtool improvements:
- Added a 'devtool latest-version' subcommand to get the latest available version upstream for a recipe
- devtool upgrade now defaults to latest upstream version/commit when upgrading recipes
- devtool upgrade now automatically handles a change in source subdirectory in the upstream archive
- devtool upgrade will now handle and report license checksum changes
- devtool upgrade has improved performance and now shows progress when adding files
- devtool find-recipe and edit-recipe now always work with any recipe
- devtool finish now ensures the source repository is clean before proceeding
- devtool finish now has a dry-run option so you can see the changes that will be made before applying them
- devtool finish now has a --force-patch-refresh option to allow refreshing patch context
- devtool can now deal with conditional patches (those added to SRC_URI using an override)
- devtool search will now also look in the recipe cache, so it can show unbuilt recipes in the results
* initramfs improvements:
- core-image-minimal-initramfs now uses initramfs-framework for initialization
- New 'initramfs-live-boot-tiny' uses busybox-mdev instead of udev for a smaller footprint
- New 'exec' initramfs-framework module allows executing a set of arbitrary scripts
- initramfs-live-install can now be built for aarch64
- initramfs-framework: allow use of LABEL= to find the rootfs using its partition label
- live image build will now show a warning if the initramfs is invalid
* cmake integration improvements:
- Allow the generator to be changed and default to Ninja for faster builds for cmake-using recipes
- Allow target names for compile and install to be overridden
- Always put cmake package files in -dev packages
* BitBake changes:
- Reworked --runall option and added --runonly option
- Graph (dot) files produced by bitbake -g are now sorted for easier comparisons
- Make contrib/dump_cache.py dump everything
* Toaster web UI improvements:
- Updated to Django 1.11
- Added a "nobuild" command-line option to disable building from the UI (whilst still enabling sharing of build statistics)
- Highlight capture of command-line builds on frontpage
* Icecream distributed compilation improvements:
- Add Icecream support to SDK if icecc class is inherited by the build
- icecc-create-env: add option to add arbitrary extra tools
- icecc-create-env: allow multiple tool aliases
- icecc-create-env: allow logging to a file
- Add ICECC_ENV_DEBUG variable to allow passing extra debug options to icecc-create-env
* Miscellaneous script improvements:
- oe-pkgdata-util: Add support for RPROVIDES
- oe-pkgdata-util: add --long option to list-pkg-files to show sizes
- oe-depends-dot: add script to make handling .dot files (produced by bitbake -g or buildhistory) easier
- runqemu: Allow the user to override the device tree option
- crosstap: replace script with new python based implementation
- buildhistory-diff: add support for colourising the output
- scripts/contrib/bbvars.py: rewritten to use tinfoil
* New recipes: glide, gst-validate, initramfs-live-boot-tiny, libpipeline, libtest-needs-perl, meson, musl-utils, systemd-bootconf
* Replaced outdated man with man-db
* Restructured python/python3 packaging and replaced it with autopackaging for better maintainability
* Added pypi class to simplify python recipes that fetch from pypi.org (from meta-python)
* Added ptest-perl class and use to enable ptest functionality for a number of perl recipes
* SDK generation now runs package postinstall scripts
* SDK now provides a post-relocate script hook
* Enabled ptests as part of runtime tests by default (where possible)
* kern-tools: make fuzzy matching of machine optional
* kernel-uboot: support Image kernel type for arm64
* kexec-tools: add systemd support for kdump
* godep.bbclass: Add helper class to enable go-dep tool
* Added new glide class to make using Glide for Go packaging easier
* Ensure that rootfs gets mounted ro when read-only-rootfs is active
* Extend recipes to nativesdk: diffutils, libcroco, libtirpc
* Extend recipes to native: diffutils, libmnl, libtirpc
* qemu: use upstream swtpm support
* coreutils: add PACKAGECONFIG for single-binary feature
* libarchive: Enable xz and lzo by default
* grub-efi: add configfile as default built-in
* systemd: add systemd-bootconf recipe
* systemd-boot: add package that installs to boot
* cve-check: provide CVE_VERSION variable to allow recipes to override their version
* oe-init-build-env now searches for bitbake outside of oe-core
* Added the addto_recipe_sysroot task for cross recipes (in addition to native)
* SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS now supports a wildcard on the left side of a dependency (to exclude anything depending on a particular recipe)
* distrodata: make upstream version check more useful for git upstreams
* distrodata: added a utility script to compare list of recipes
* image: add image-combined-dbg helper class
* connman: Implement subnet route in session
* useradd-staticids: improve error messages to suggest corrective action for missing user/group IDs
* sstate.bbclass: added progress bars when removing items from the sysroots
* waf.bbclass: added progress reporting for compile task
* bin_package: error out if source directory doesn't actually contain anything
* Refreshed patches across a number of recipes
* common-licenses: added BSD-1-Clause

---------------------
Security Fixes
---------------------
* bind: CVE-2017-3142 and CVE-2017-3143, CVE-2017-3141, CVE-2017-3140
* binutils: CVE-2017-15939, CVE-2017-15938, CVE-2017-15225, CVE-2017-15025, CVE-2017-15024, CVE-2017-15023, CVE-2017-15022, CVE-2017-15021, CVE-2017-15020, CVE-2017-14974, CVE-2017-14940, CVE-2017-14939, CVE-2017-14938, CVE-2017-14934, CVE-2017-14933, CVE-2017-14932, CVE-2017-14930, CVE-2017-14745, CVE-2017-14729, CVE-2017-14529, CVE-2017-14333, CVE-2017-14130, CVE-2017-14129, CVE-2017-14128, CVE-2017-13757, CVE-2017-13716, CVE-2017-13710, CVE-2017-12967, CVE-2017-12799, CVE-2017-12459, CVE-2017-12458, CVE-2017-12457, CVE-2017-12456, CVE-2017-12455, CVE-2017-12454, CVE-2017-12453, CVE-2017-12452, CVE-2017-12451, CVE-2017-12450, CVE-2017-12449, CVE-2017-12448
* bluez5: CVE-2017-1000250
* busybox: CVE-2011-5325, CVE-2017-16544, CVE-2017-15873
* curl: CVE-2017-1000254
* dhcp: CVE-2017-3144
* glibc: CVE-2017-15671, CVE-2017-16997, CVE-2017-17426
* icu: CVE-2017-14952
* lame: CVE-2017-9412, CVE-2017-9410, CVE-2017-9411, CVE-2017-13712
* libpcre2: CVE-2017-8399
* libvorbis: CVE-2017-14633, CVE-2017-14632, CVE-2018-5146
* libxcursor: CVE-2017-16612
* libxfont: CVE-2017-16611
* libxfont2: CVE-2017-16611
* libxres: CVE-2013-1988
* nss: CVE-2017-7805
* openssl: CVE-2017-3736, CVE-2017-3735
* openssl10: CVE-2017-3736, CVE-2017-3735
* patch: CVE-2018-6951, CVE-2018-1000156
* perl: CVE-2017-12883
* python3: CVE-2017-1000158
* python3-native: CVE-2017-1000158
* qemu: CVE-2017-17381, CVE-2017-15124
* tiff: CVE-2017-99935, CVE-2017-18013, CVE-2018-5784
* webkitgtk: CVE-2017-5753 and CVE-2017-5715
* wget: CVE-2017-13089 CVE-2017-13090 CVE-2017-6508
* xorg-xserver: CVEs 2017-12176, CVE-2017-12177, CVE-2017-12178, CVE-2017-12179, CVE-2017-12180, CVE-2017-12181, CVE-2017-12182, CVE-2017-12183, CVE-2017-12184, CVE-2017-12185, CVE-2017-12186, CVE 2017-12187

---------------
Updates
--------------

* adwaita-icon-theme: update to 3.26.0
* alsa-lib: 1.1.4.1 -> 1.1.5
* alsa-plugins: 1.1.4 -> 1.1.5
* alsa-tools: 1.1.3 -> 1.1.5
* alsa-utils: 1.1.4 -> 1.1.5
* apr: 1.6.2 -> 1.6.3
* apr-util: 1.6.0 -> 1.6.1
* assimp: upgrade to version 4.1.0
* atk: upgrade to version 2.26.1
* at-spi2-atk: 2.26.0 -> 2.26.1
* at-spi2-core: 2.26.0 -> 2.26.2
* avahi: upgrade to 0.7
* babeltrace: update to 1.5.4
* bash: 4.4 -> 4.4.12
* bind: update to 9.10.6
* binutils: Upgrade to 2.30 release
* blktrace: 1.1.0+gitX -> 1.2.0+gitX
* bluez5: 5.46 -> 5.48
* boost: update to 1.66.0
* btrfs-tools: update to 4.13.3
* busybox: 1.24.1 -> 1.27.2
* cairo: 1.14.10 -> 1.14.12
* ccache: 3.3.4 -> 3.3.5
* clutter-gtk-1.0: update to 1.8.4
* cmake: Upgrade to 3.10.3
* connman: upgrade 1.34 -> 1.35
* coreutils: upgrade to 8.29
* cups: upgrade to 2.2.6
* curl: upgrade to 7.58.0
* dbus-test: upgrade to 1.12.2
* dbus: upgrade to 1.12.2
* debianutils: update to 4.8.4
* dnf: update to 2.7.5
* dtc: update to 1.4.5
* e2fsprogs: 1.43.5 -> 1.43.8
* epiphany: upgrade to 3.26.6
* ethtool: upgrade to 4.13
* eudev: bump up to version 3.2.5
* expat: upgrade to 2.2.5
* expect: update to 5.45.4
* ffmpeg: update to 3.4.2
* file: 5.31 -> 5.32
* fontconfig: update to 2.12.6
* freetype: upgrade to version 2.9
* gawk: upgrade to 4.2.0
* gcc6: Upgrade to 6.4
* gcc: Upgrade 7.2 -> 7.3
* gdbm: 1.13 -> 1.14.1
* gdb: Upgrade to 8.0.1
* gdk-pixbuf: update to 2.36.11
* git: 2.13.3 -> 2.16.1
* glew: update to 2.1.0
* glib-2.0: upgrade to version 2.54.3
* glibc: Upgrade to 2.27 release + bugfixes
* glib-networking: update to 2.54.1
* gnome-desktop3: Update to 3.26.2
* gnupg: upgrade to 2.2.4
* gnutls: update to 3.6.1
* gobject-introspection: update to 1.54.1
* go-dep: Upgrade to 0.4.1
* go: add 1.10.1
* go: Upgrade 1.9 to 1.9.4 stable release
* gpgme: 1.9.0 -> 1.10.0
* gsettings-desktop-schemas: update to 3.24.1
* gst-examples: upgrade to latest revision
* gstreamer1.0-libav: upgrade to version 1.12.3
* gstreamer1.0-omx: upgrade to version 1.12.3
* gstreamer1.0-plugins-bad: upgrade to version 1.12.3
* gstreamer1.0-plugins-base: upgrade to version 1.12.3
* gstreamer1.0-plugins-good: upgrade to version 1.12.3
* gstreamer1.0-plugins-ugly: upgrade to version 1.12.3
* gstreamer1.0-python: upgrade to version 1.12.3
* gstreamer1.0-rtsp-server: upgrade to version 1.12.3
* gstreamer1.0: upgrade to version 1.12.4
* gstreamer1.0-vaapi: upgrade to version 1.12.3
* gtk+3: upgrade to version 3.22.28
* gtk-doc: update to 1.27
* gtk-icon-utils-native: upgrade to version 3.22.28
* gtk+: upgrade to version 2.24.32
* gzip: 1.8 -> 1.9
* harfbuzz: upgrade to version 1.7.5
* hdparm: 9.52 -> 9.53
* help2man-native: 1.47.4 -> 1.47.5
* hicolor-icon-theme: update to 0.17
* i2c-tools: upgrade to 4.0
* icu: 60.1 -> 60.2
* icu: update to 60.1
* iproute2: upgrade to 4.14.1
* iptables: 1.6.1 -> 1.6.2
* iputils: update to 20161105
* iso-codes: update to 3.77
* iw: 4.9 -> 4.14
* json-c: update to 0.13
* json-glib: update to 1.4.2
* kexec-tools: 2.0.14 -> 2.0.16
* kmod: 24 -> 25
* lame: 3.99.5 -> 3.100
* less: 487 -> 529
* libassuan: update to 2.5.1
* libatomic-ops: upgrade to 7.6.2
* libbsd: update to 0.8.7
* libcheck: Upgrade to 0.12.0
* libdnf: update to 0.11.1
* libdrm: upgrade to 2.4.91
* libepoxy: update to version 1.5.0
* liberror-perl: 0.17024 -> 0.17025
* libevdev: upgrade to version 1.5.8
* libgcrypt: update from version 1.8.0 to 1.8.2
* libgudev: update to 232
* libinput: upgrade to version 1.9.4
* libjpeg-turbo: upgrade to 1.5.3
* libmpc: upgrade to 1.1.0
* libnl: 3.2.29 -> 3.4.0
* libogg: upgrade to 1.3.3
* libpciaccess: update to 0.14
* libpcre2: update to 10.30
* libpng: Upgrade 1.6.31 -> 1.6.34
* libproxy: upgrade to 0.4.15
* librepo: update to 1.8.1
* librsvg: update to 2.40.20
* libsdl2: 2.0.5 -> 2.0.8
* libsolv: upgrade to version 0.6.32
* libsoup-2.4: upgrade to version 2.60.3
* libtasn1: upgrade to version 4.13
* libunistring: update version to 0.9.9
* libunwind: 1.2 -> 1.2.1
* liburcu: update to 0.10.1
* liburi-perl: upgrade 1.72 -> 1.73
* libva: upgrade to 2.1.0
* libva-utils: upgrade to 2.1.0
* libwebp: update to 0.6.1
* libxcursor: update to 1.1.15 plus sec fixes
* libxfont2: update to 2.0.3 with sec fix
* libxfont: update 1.5.4 with sec fix
* libxkbcommon: update to 0.8.0
* libxml2: 2.9.4 -> 2.9.7
* libxml-namespacesupport-perl: upgrade to 1.12.9
* libxslt: update to 1.1.32
* lighttpd: update to 1.4.48
* linux-firmware: upgrade to 4c0bf11 revision
* linux-libc-headers: update to 4.15.7
* linux-yocto/4.12: update to v4.12.21
* linux-yocto/4.14: update to v4.14.30
* linux-yocto/4.15: update to v4.15.13
* linux-yocto-dev: update to v4.16-rcX
* llvm: Upgrade to 6.0 release
* logrotate: 3.12.3 -> 3.13.0
* lsbinitscripts: update to 9.79
* lsb: update to 5.0
* ltp: bump to release 20180118
* lttng-modules: update to v2.10.5 for kernel 4.15
* lttng-ust: upgrade 2.9.1 -> 2.10.1
* man-db: replace the outdated man implementation
* man-pages: 4.11 -> 4.14
* mc: upgrade to 4.8.20
* mesa: Upgrade to 17.3.8
* meson: upgrade to 0.44.1
* mmc-utils: Upgrade to latest revision (7bcad17117)
* mpg123: update to 1.25.10
* mtd-utils: Bump revision to 1bfee866
* musl: Update to latest master (618b18c78e)
* nasm: upgrade 2.13.01 -> 2.13.03
* ncurses: 6.0+20170715 -> 6.0+20171125
* nettle: update to 3.4 and cleanup
* ninja: Upgrade from 1.7.2 to major release 1.8.2
* nspr: update to 4.19
* nss: update to 3.35
* ofono: upgrade to version 1.22
* openssh: update to 7.6
* openssl: update 1.1 version to 1.1.0h
* openssl: update to 1.0.2o
* opkg: upgrade to version 0.3.6
* opkg-utils: upgrade to version 0.3.6
* orc: upgrade to 0.4.28
* pango: upgrade to version 1.40.14
* patch:2.7.5 -> 2.7.6
* pciutils: upgrade to 3.5.6
* piglit: upgrade to current git master
* pigz: 2.3.4 -> 2.4
* pinentry: update to 1.1.0
* pkgconf: upgrade to version 1.4.2
* powertop: update to v2.9
* prelink_git.bb: Update recipe to newest commit
* pseudo: update to latest master
* psmisc: update to 23.0
* ptest-runner: Upgrade to 2.1.1
* pulseaudio: 10.0 -> 11.1
* puzzles: upgrade to latest revision
* python3-dbus: update to version 1.2.6
* python3-git: update to 2.1.8
* python3-native: update to version 3.5.5 to fix security issues
* python3-numpy: upgrade to 1.13.3
* python3-pip: update to 9.0.2
* python3-pycairo: update to 1.15.6
* python3-pygobject: update to 3.28.1
* python3-six: update to 1.11.0
* python3: update to version 3.5.5 to fix security issues
* python-gitdb: upgrade to v2.0.3
* python-numpy: update to 1.14.2
* python-scons: upgrade to v3.0.1
* python*-setuptools: update to 39.0.0
* python: Upgrade both python and python-native to 2.7.14
* qemu: upgrade to 2.11.1
* quota: upgrade to 4.04
* rpm: update to 4.14.1
* rsync: update to 3.1.3
* ruby: upgrade to 2.5.0
* screen: upgrade to version 4.6.2
* shared-mime-info: update to 1.9
* slang: 2.3.1a -> 2.3.2
* sqlite3: upgrade to version 3.22.0
* strace: 4.18 -> 4.20
* subversion: upgrade 1.9.6 -> 1.9.7
* sudo: upgrade to 1.8.22
* sysprof: update to 3.26.1
* sysstat: upgrade to 11.7.1
* systemd-bootchart: upgrade to v233
* systemd-boot: upgrade to 237
* systemd: upgrade to 237
* systemtap: 3.1 -> 3.2
* tar: 1.29 -> 1.30
* tcl: update to 8.6.8
* texinfo: upgrade to 6.5
* tiff: 4.0.8 -> 4.0.9
* time: 1.7 -> 1.8
* trace-cmd: update to 2.7
* tzcode-native: update to 2018d
* tzdata: update to 2018d
* u-boot: Upgrade to 2018.01 release
* usbutils: 008 -> 009
* util-linux: upgrade to 2.31
* vala: update to 0.38.8
* vte: upgrade to version 0.50.2
* vulkan: upgrade to version 1.0.65.2
* wayland : Bump to version 1.14.0
* wayland-protocols: upgrade to 1.13
* webkitgtk: update to 2.18.6
* weston: Bump version to 3.0.0
* wget: update to 1.19.4
* x264: upgrade to latest revision
* xdg-utils: update to 1.1.2
* xf86-input-libinput: update to 0.26.0
* xkeyboard-config: upgrade to 2.22
* xorg-xserver: update to 1.19.6