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Despite depending heavily on tools, the kernel project often seems to under-invest in the development of those tools. There has been progress in that area, though. At the 2025 Maintainers Summit, Konstantin Ryabitsev, who is (among other things) the author of b4, led a session on ways in which the kernel's tools could be improved to make the development process more efficient and accessible.

Security updates have been issued by AlmaLinux (firefox, grafana, kernel, libsoup3, mysql8.4, and wireshark), Debian (ruby-git, ruby-sidekiq, thunderbird, and vlc), Fedora (apptainer, chromium, firefox, golangci-lint, libpng, and xkbcomp), Mageia (golang), SUSE (binutils, chromium, firefox, gegl, go1.25, govulncheck-vulndb, hauler, kernel, keylime, libpng12, pgadmin4, postgresql16, python, python-Django, python-django, python3, python311, rhino, thunderbird, unbound, and xkbcomp), and Ubuntu (usbmuxd).

Linus Torvalds released 6.19-rc1 and closed the 6.19 merge window on December 14 (Japan time), after having pulled 12,314 non-merge commits into the mainline. Over 8,000 of those commits came in after our first 6.19 merge-window summary was written. The second part of the merge window was focused on drivers, but brought in a number of other changes as well.

Linus has released 6.19-rc1, perhaps a bit earlier than expected.

So it's Sunday afternoon in the part of the world where I am now, so if somebody was looking at trying to limbo under the merge window timing with one last pull request and is taken by surprise by the slightly unusual timing of the rc1 release, that failed.

Teaching moment, or random capricious acts? You be the judge.

Ariadne Conill is exploring a capability-based approach to privilege escalation on Linux systems.

Inspired by the object-capability model, I've been working on a project named capsudo. Instead of treating privilege escalation as a temporary change of identity, capsudo reframes it as a mediated interaction with a service called capsudod that holds specific authority, which may range from full root privileges to a narrowly scoped set of capabilities depending on how it is deployed.

The ability to write kernel code in Rust was explicitly added as an experiment — if things did not go well, Rust would be removed again. At the 2025 Maintainers Summit, a session was held to evaluate the state of that experiment, and to decide whether the time had come to declare the result to be a success. The (arguably unsurprising) conclusion was that the experiment is indeed a success, but there were some interesting points made along the way.

Greg Kroah-Hartman has released the 6.18.1, 6.17.12, and 6.12.62 stable kernels. Each contains important fixes; users of those kernels are advised to upgrade.

One of the key components in the kernel's development process is the linux-next repository. Every day, a large number of branches, each containing commits intended for the next kernel development cycle, is pulled into linux-next and integrated. If there are conflicts between branches, the linux-next process will reveal them. In theory, many other types of problems can be found as well. Some developers feel that linux-next does not work as well as it could, though. At the 2025 Maintainers Summit, Mark Brown, who helps to keep linux-next going, led a session on how it could be made to work more effectively.

KDE has announced the release of KDE Gear 25.12. This release adds more "extractors" to the Itinerary travel-assistant application, improved Git support in the Kate text editor, better PDF export in Konqueror, and much more. See the changelog for all new features, improvements, and bug fixes.

Security updates have been issued by AlmaLinux (firefox, luksmeta, mysql, mysql:8.0, mysql:8.4, tomcat, and wireshark), Debian (chromium, kernel, and tzdata), Fedora (brotli, dr_libs, perl-Alien-Brotli, python-urllib3, singularity-ce, wireshark, and yarnpkg), Oracle (firefox, grafana, lasso, libsoup3, luksmeta, ruby, ruby:3.3, tomcat, and wireshark), Slackware (mozilla), SUSE (container-suseconnect, kubernetes-client, libpoppler-cpp2, postgresql14, postgresql15, and python3), and Ubuntu (c-ares, keystone, linux, linux-aws, linux-aws-5.15, linux-azure, linux-gcp, linux-gcp-5.15, linux-gke, linux-gkeop, linux-hwe-5.15, linux-ibm, linux-ibm-5.15, linux-intel-iotg, linux-intel-iotg-5.15, linux-lowlatency, linux-lowlatency-hwe-5.15, linux-nvidia, linux-nvidia-tegra, linux-nvidia-tegra-5.15, linux-nvidia-tegra-igx, linux-oracle, linux-oracle-5.15, linux-xilinx-zynqmp, linux-azure, linux-azure-4.15, linux-oracle,, linux-fips, linux-aws-fips, linux-azure-fips, linux-gcp-fips, linux-fips, linux-aws-fips, linux-gcp-fips, linux-hwe-6.8, linux-oracle-6.8, linux-raspi, linux-realtime, linux-intel-iot-realtime, and python-urllib3).

Version 24.04 LTS of the Ubuntu-based Pop!_OS distribution has been released with the COSMIC Desktop Environment:

Today is special not only in that it's the culmination of over three years of work, but even more so in that System76 has built a complete desktop environment for the open source community. We're proud of this contribution to the open source ecosystem. COSMIC is built on the ethos that the best open source projects enable people to not only use them, but to build with them. COSMIC is modular and composable. It's the flagship experience for Pop!_OS in its own way, and can be adapted by anyone that wants to build their own unique user experience for Linux.

In addition to the COSMIC desktop environment, Pop!_OS is now available for Arm computers with the 24.04 LTS release, and the distribution has added hybrid graphics support for better battery life. LWN covered an alpha version of COSMIC in August 2024.

Version 1.92.0 of Rust has been released. This release includes a number of stabilized APIs, emits unwind tables by default on Linux, validates input to #[macro_export], and much more. See the separate release notes for Rust, Cargo, and Clippy.

The first topic of discussion at the 2025 Maintainers Summit has been in the air for a while: what role — if any — should machine-learning-based tools have in the kernel development process? While there has been a fair amount of controversy around these tools, and concerns remain, it seems that the kernel community, or at least its high-level maintainership, is comfortable with these tools becoming a significant part of the development process.

Security updates have been issued by Debian (ffmpeg, firefox-esr, libsndfile, and rear), Fedora (httpd, perl-CGI-Simple, and tinyproxy), Oracle (firefox, kernel, libsoup, mysql8.4, tigervnc, tomcat, tomcat9, and uek-kernel), SUSE (alloy, curl, dovecot24, fontforge, glib2, himmelblau, java-17-openjdk, java-21-openjdk, kernel, krb5, lasso, libvirt, mozjs128, mysql-connector-java, nvidia-open-driver-G07-signed-check, openssh, poppler, postgresql17, postgresql18, python-cbor2, python-Django, python310, python311-Django, runc, strongswan, tomcat11, and xwayland), and Ubuntu (binutils, libpng1.6, linux, linux-aws, linux-aws-5.4, linux-gcp, linux-gcp-5.4, linux-hwe-5.4, linux-ibm, linux-ibm-5.4, linux-kvm, linux-oracle, linux-xilinx-zynqmp, linux, linux-aws, linux-aws-6.14, linux-gcp, linux-hwe-6.14, linux-raspi, linux, linux-aws, linux-gcp, linux-realtime, and qtbase-opensource-src).

Inside this week's LWN.net Weekly Edition:

• Front: Rust in CPython; Python frozendict; Bazzite; IETF post-quantum disagreement; Distrobox; 6.19 merge window; Leaving the TAB.
• Briefs: Let's Encrypt retrospective; PKI infrastructure; Rust in kernel to stay; CNA series; Alpine 3.23.0; cmocka 2.0; Firefox 146; 2024 Free Software Awards; Quotes; ...
• Announcements: Newsletters, conferences, security updates, patches, and more.

Let's Encrypt has published a retrospective that covers the decade since it published its first publicly trusted certificate in September 2015:

In March 2016, we issued our one millionth certificate. Just two years later, in September 2018, we were issuing a million certificates every day. In 2020 we reached a billion total certificates issued and as of late 2025 we're frequently issuing ten million certificates per day. We're now on track to reach a billion active sites, probably sometime in the coming year.

Greg Kroah-Hartman is writing a series of blog posts about Linux becoming a Certificate Numbering Authority (CNA):

It's been almost 2 full years since Linux became a CNA (Certificate Numbering Authority) which meant that we (i.e. the kernel.org community) are now responsible for issuing all CVEs for the Linux kernel. During this time, we've become one of the largest creators of CVEs by quantity, going from nothing to number 3 in 2024 to number 1 in 2025. Naturally, this has caused some questions about how we are both doing all of this work, and how people can keep track of it.

So far, Kroah-Hartman has published the introductory post, as well as a detailed post about kernel version numbers that is well worth reading.

Linux containers have made it reasonably easy to develop, distribute, and deploy server applications along with all the distribution dependencies that they need. For example, anyone can deploy and run a Debian-based PostgreSQL container on a Fedora Linux host. Distrobox is a project that is designed to bring the cross-distribution compatibility to the desktop and allow users to mix-and-match Linux distributions without fussing with dual-booting, virtual machines, or multiple computers. It is an ideal way to install additional software on image-based systems, such as Fedora's Atomic Desktops or Bazzite, and also provides a convenient way to move a development environment or favorite applications to a new system.

Security updates have been issued by AlmaLinux (abrt and kernel), Debian (libpng1.6, libsoup2.4, pdns-recursor, webkit2gtk, and wordpress), Fedora (imhex, libwebsockets, lunasvg, python3-docs, and python3.14), Mageia (python3 and webkit2), Red Hat (abrt, firefox, mysql8.4, and postgresql:15), Slackware (mozilla), SUSE (gegl, gnutls, go1.24, go1.25, libpng16-16, openssh, postgresql13, python-Jinja2, and sssd), and Ubuntu (fonttools and netty).

The topic of the Rust experiment was just discussed at the annual Maintainers Summit. The consensus among the assembled developers is that Rust in the kernel is no longer experimental — it is now a core part of the kernel and is here to stay. So the "experimental" tag will be coming off. Congratulations are in order for all of the Rust for Linux team.

(Stay tuned for details in our Maintainers Summit coverage.)