• Front: Android vendor hooks; Reproducible builds and kernel integrity; Rust data structures; NFS server changes; Setting no_new_privs for PID 1; Rust XArray; Rust cross-crate declarations; 7.3 statistics; Nix flakes.
• Briefs: eMudhra CA compromise; PHP RCEs; Node.js and musl vulnerabilities; GNOME OS; OpenBSD 8.0; Ubuntu 26.10; TAB results; Quotes; ...
• Announcements: Newsletters, conferences, security updates, patches, and more.

To fix the OOM problem, the PHP security team developed several competing approaches, but each came with its own trade-offs: backward compatibility breaks, new denial-of-service potential, or requiring changes to many third-party extensions which seemed impossible to coordinate. The PHP security team, operating on consensus, struggled to choose between these and feared the repercussions of shipping the wrong choice. Combined with the lack of a known path to remote code execution and the small team of core developers with the necessary deep knowledge of the engine occupied with many responsibilities, this decision process caused work on a fix to stall and restart repeatedly over months. We won't pretend otherwise: the delay was a structural failure, caused by both the security team's decision process and its lack of resources.

The Node.js project has released a number of security updates to fix, among other vulnerabilities, a remote-code-execution bug affecting programs that use Brotli compression. And, in case any programmers who use compiled languages thought they could relax, the musl libc project has also announced a new vulnerability: an out-of-bounds write that could potentially lead to remote code execution, although that has not been demonstrated.

One of our biggest challenges has been developing Tyr while the Rust kernel abstractions and driver interfaces are also being developed. As the driver interfaces are naturally revised and improved, we have rewritten Tyr several times to adapt to the larger Rust ecosystem. This not only makes progress much slower than it would be with a mature API, but also stalls progress for capabilities, such as job scheduling, while the abstraction is properly designed, reviewed, tested, and merged upstream.

But working in this evolving environment is also precisely where Tyr is able to provide the most value. As a user of these new Rust abstractions, Tyr helps to expose their requirements and limitations.

Nix flakes are an experimental feature of the Nix package-management tool designed to build projects in a more self-contained and reproducible way. Despite the feature's experimental status, it has become increasingly popular for open-source projects to publish flake.nix files that offer predefined development environments and build automation even when those repositories may not offer an upstream package or module for the NixOS Linux distribution. Although Nix flakes have a complicated history, and the path for stabilization is uncertain, flakes can provide useful capabilities for projects that choose to include them.

The PHP project has published PHP versions 8.5.12, 8.4.27, 8.3.36 and 8.2.35 to address two critical vulnerabilities that could allow unauthenticated remote code execution.

Who is at risk: all PHP installations serving web requests, including PHP-FPM, Apache with mod_php, php-cgi, FrankenPHP and LiteSpeed. We consider the risk highest for mod_php, with a demonstrated exploit where an unauthenticated request can trigger the attack before any application code runs.

The vulnerabilities:

• RCE via OOM corruption, CVE-2026-109618 (GHSA-w8hw-w9fx-j79w): out-of-memory handling can interrupt PHP while internal request data is only partially initialized. Request cleanup may then treat the invalid data as valid.
• RCE via stale global state, CVE-2026-109619 (GHSA-6wmf-4rv5-p3rp): request-owned internal state can survive after its backing memory has been freed. A later request handled by the same worker may use that stale state before normal initialization resets it.

PHP versions older than 8.1 will not receive updates from the project, though the project has provided some patches for PHP 7.4, PHP 8.0, and PHP 8.1 to assist in creating backports. According to the announcement, Linux distributions and vendors received patches in advance, so updated packages should be coming soon.

Greg Kroah-Hartman has announced the release of the 7.2.12, 6.18.58, 6.12.114, and 6.6.160 stable kernels. Each contains a number of important fixes; users are advised to upgrade.

Setuid (and setgid) binaries have long been a source of headaches, and security vulnerabilities, on Linux systems. They are largely seen as something to be avoided; SUSE's security team, for example, forbids the inclusion of setuid or setgid binaries in packages unless they have been reviewed and explicitly allowed. Thorsten Kukuk wants to go a step further and disallow them entirely. At the 2026 All Systems Go! conference, he spoke about his work to disable setuid system-wide, as well as some of the hurdles that remain.

The work to support block sizes larger than the page size on XFS has been difficult. Many users of XFS run stable kernels, which means that they aren't testing new XFS code as it is released. That has made Daniel Gomez wonder whether adopting Rust for some of the data structures underlying XFS, particularly XArrays, could reduce the number of bugs lurking in the code. At Kangrejos 2026, he led a discussion about the potential problems with converting XArray to Rust. The assembled kernel developers had a number of reasons to be cautious about replacing the XArray code, but Gomez was determined to experiment with the possibility, citing both security and performance improvements.

Mozilla has announced that it has received a report that private keys associated with eight eMudhra intermediate certificates have been compromised:

These keys could allow attackers to issue fraudulent HTTPS certificates for websites they do not control. An attacker who could intercept a user's connection could use those certificates to impersonate websites and potentially read or modify traffic.

Mozilla has blocked the affected certificates using its OneCRL centralized list of revoked certificates, and has updated the trusted certificate list in Network Security Services (NSS) 3.131.1.

There is a single-page site about the compromise that goes into more detail. According to the site the certificates have also been blocked in Chrome since October 17, Apple devices since the 19th, and Microsoft blocked the certificates on the 20th. There is also a table that displays whether a browser or other client still trusts the compromised certificates.

The NetBSD foundation has issued instructions to block the certificates on NetBSD installations. Users of other browsers and operating systems may wish to check for updates or guidance to disable the compromised certificates.

OpenBSD 8.0 has been released. There are many new features, including the addition of hibernate support for arm64, an increase in the kernel virtual address space for amd64 to 512GB, quite a few improvements for the qwx driver that supports Qualcomm WiFi 6 devices, and much more. See the full changelog for details.

Mike Rapoport has announced the release of the video recordings from the 2026 Linux Plumbers Conference (LPC), which was held in Prague from October 5 through October 7. Find the complete set via the YouTube playlist or look for the video links in the schedule. See also LWN's coverage of talks from LPC.

Rust has several ad-hoc mechanisms to allow user code to influence how the standard library executes. For example, custom panic handlers and custom allocators both involve registering functions that core standard library code needs to call. With more similar features planned, Jana Dönszelmann spotted the developing pattern and put together a general solution, introducing a safer, checked analogue of C's weak symbol linking. At Kangrejos 2026, she explained how this new language feature works, and proposed using it to clean up the kernel's handling of integer overflows in Rust code.

It's Sunday afternoon, and this week I somehow kept my wits together long enough to keep track of the day of the week, so the release isn't randomly delayed. Will wonders never cease?

Anyway, nothing very special seems to have happened this last week, so as expected the final 7.3 is out, and thus tomorrow the merge window for 7.4 opens. Except I'm on my annual family vacation, so instead of merging anything first thing in the morning, I'll spend most of the day on a boat and under water. I'll get back to merging in the afternoon, but I expect my schedule to be a bit unusual for a while.

This release is a record-breaker on all fronts; it brought in 18,765 non-merge commits from 3,021 developers, 807 of whom were first-time kernel developers.

Significant changes in this release include some significant binfmt_misc extensions, some group-scheduling work aimed at improving performance on large systems, the new failfs filesystem that fails all operations, the fchroot() system call, global per-CPU data for BPF programs, the completion of the sched_ext subscheduler feature, working-set tracking for virtual machines, alternative data-stream support in the ntfs3 filesystem, a long list of SMB server improvements, and much more. See the LWN merge-window summaries (part 1, part 2) and the KernelNewbies 7.3 page for details.