Vue lecture
Local DoS attack vectors in seunshare 3.10 (SUSE Security Team Blog)
The SUSE Security Team Blog has a post with an analysis of seunshare, which is used by SELinux to confine untrusted programs. During a review of version 3.10 of the program, the team identified two local Denial-of-Service (DoS) vectors.
Since seunshare is supposed to run on SELinux-enabled systems, it is important to understand what kind of privilege escalation can be achieved when vulnerabilities are exploited in a setuid-root binary like this. Many SELinux-enabled systems, such as Fedora and openSUSE, ship with the "targeted" SELinux policy by default. This policy is focused on confining well-known system services, but assigns an unconfined SELinux context to interactive users by default to achieve a balance between security and usability.
There is currently no domain transition from the unconfined domain to the more restricted seunshare_t defined in the SELinux policy for seunshare. This means the execution of seunshare continues in the unconfined domain. Thus in the context of attacks carried out by interactive users, the impact of the vulnerabilities below will be a root-like privilege escalation despite the system running in SELinux enforced mode.
See the post for the full write-up of the team's discoveries and timeline. The vulnerabilities have been fixed in version 3.11.
Security updates for Wednesday
[$] LWN.net Weekly Edition for July 9, 2026
- Front: Cryptography API; Iomap explanation; Negative dentries; Faster RCUs and lockless allocation for BPF; LLMs in memory-management code
- Briefs: Guix vulnerabilities; OpenSSH 10.4; trusted publishing; kernel archive; CalyxOS; Quotes; ...
- Announcements: Newsletters, conferences, security updates, patches, and more.
[$] Progress in modernizing kernel cryptography
At the 2026 Linux Security Summit North America, Eric Biggers spoke about some of the problems with the kernel's cryptography framework, as well as the recent progress in adding library APIs to allow developers to use cryptographic functions without using the traditional crypto API. He walked through a couple of examples to demonstrate the frailty of the original API and showed how the new library API made life easier for developers and kernel maintainers.
Woodruff: You shouldn't trust trusted publishing
William Woodruff, better known online as "yossarian", has published a blog post to make the case that users should not place their trust in trusted publishing:
Trusted Publishing is a mechanism for establishing trust between an external machine identity (like a CI/CD workflow) and one or more projects on a package index/registry. The "trust" in "Trusted Publishing" refers to that trust relationship, and not to anything else.
It is not, and cannot be, a signal for package trust or quality. You cannot use it to determine whether a package is safe or "good," and PyPI consciously stymies attempts to misuse it for that purpose by not rendering it as a "green checkmark" or anything else of the sort.
Or as another framing: Trusted Publishing is just a form of authentication. It doesn't tell you anything other than that an upload was authenticated, which all uploads to PyPI are.
LWN covered trusted publishing in June.
Security updates for Tuesday
OpenSSH 10.4 released
OpenSSH 10.4 has been released. In addition to a number of security and bug fixes, there are a few notable changes; this release adds experimental support for a composite post-quantum signature scheme combining ML-DSA 44 and Ed25519 as described in this IETF draft. With 10.4, if OpenSSH is compiled with sandbox support it will fail on Linux systems that have not enabled SECCOMP or NO_NEW_PRIVS; prior to this release, sshd would log an error but continue operation. See the release notes for a full list of changes.
Security updates for Monday
Seven stable kernels for Saturday including two security fixes
Greg Kroah-Hartman has announced the release of the 7.1.3, 6.18.38, 6.12.95, 6.6.144, 6.1.177, 5.15.211, and 5.10.260 stable kernels. Several kernels in this batch include a fix for a vulnerability introduced in the 6.0 kernel in IPv6 (CVE-2026-53362), which could allow an attacker to escape a container and gain root access.
There is also a fix for a use-after-free bug in KVM (CVE-2026-53359) that was introduced in the 2.6.36 kernel. As usual, each stable kernel includes a number of fixes throughout the tree. Users are advised to upgrade.
Four vulnerabilities in Guix
The GNU Guix project has announced three vulnerabilities in the guix substitute utility as well as a fourth that affects the guix pull and guix time-machine commands. The impact of the vulnerabilities ranges from remote privilege escalation to local disclosure of sensitive files.
The remote exploitation of guix substitute only requires that the vulnerable system attempt to download a binary substitute. Any configured substitute server, including ones discovered using guix-daemon's --discover option, can exploit this, and so can a man-in-the-middle (MITM), regardless of whether https is used in the substitute server urls.
The local exploitation of guix substitute only requires the ability to connect to guix-daemon's socket, which by default any user can do.
Separately, another security issue (CVE ID pending) was identified in guix pull and guix time-machine, which enables anyone who can control the channels file used by these commands to cause a file to be created or overwritten wherever the user running the command in question has permission to create them.
The project is recommending that all users upgrade guix and guix-daemon immediately. See the announcement for instructions, how to test for the vulnerabilities, the disclosure timeline, and more.
Security updates for Friday
CalyxOS is back
In August 2025, the CalyxOS privacy-focused
Android distribution announced
that it was pausing all releases while it reworked its
release process, security protocols, and changed its signing keys
following the departure of one of its founders. The project has now announced
that it is "officially back from the hiatus
" with the
7.2.2.0 release.
CalyxOS 7.2.2.0 is signed by us using a new HSM-based, open-source signing solution we designed to enhance the security of the entire signing process, ensure redundancy, and remove single points of failure. You can verify CalyxOS 7.2.2.0 and future builds following these instructions. For anyone who is interested, the security audit report of the HSM provisioning ceremony script can be found here.
In addition, we also went through significant infrastructure improvements. In particular, we have set up a cleaner server structure to streamline each release. In response to Google's less frequent AOSP source code releases, our team developed scripts to reduce the overhead in applying monthly patches and updates. Please keep in mind, additional manual steps are still needed to compensate for AOSP changes, such as requesting and storing kernel sources with each update. Currently, our lead engineer is continuing the maintenance of the base device trees for both LineageOS and CalyxOS to bridge the gap created by the absence of Google Pixel device trees.
Kernel archive /pub tree restoring
A few astute observers have noticed that some content on kernel.org had disappeared and were understandably concerned. Konstantin Ryabitsev has provided an update via social.kernel.org:
There was an unfortunate error while changing the kernel.org primary/secondary mirroring infrastructure, which resulted in the /pub tree suddenly becoming empty. No data was lost, just public mirror copies. Everything is now being restored, but deletes are fast and restores are slow, so thank you for your patience!
The incident is being tracked on the Linux Foundation's IT status page.
Spoofed email from LWN
We were made aware today of an email sent to a reader that was spoofed to appear to be from LWN. The message claimed, among other things, that we were providing personal information about the reader to another site user. As is explained in our privacy policy we do not, and would not, provide such information.
If any other readers have received an odd message from LWN, it is an attempt at a hoax; if in doubt, please check the DKIM header of the email. Any email that does come from LWN will have a proper DKIM signature in its headers.
If you receive such a message, please feel free to send it to us, with its headers intact. But to reiterate, we are not providing any user information upon request, nor banning any accounts. We hope this will not be a recurring problem.
Fedora Council proposes pausing Community Initiatives
Aoife Moloney has, on behalf of the Fedora Council, posted an
announcement that the Fedora Council is "proposing we pause the
Community Initiatives process as an official project process
"
because it has decided the current process is ineffective. It is also
closing discussion regarding the AI developer desktop
initiative covered by LWN in May.
The Fedora Objectives/Initiatives framework was never intended as a mandatory prerequisite to do the work in Fedora. It supposed to help by focusing the community on a certain work when needed, not to decide what is allowed. The AI developer desktop initiative proposal highlighted that the Community Initiatives process has failed to serve as a good framework in Fedora where new ideas can surface, receive respectful feedback, and gain Council support for work that fits the project's present and/or future. This is something that the Council must address.
As a first step, we would like to halt the community initiative process immediately. Existing initiatives in flight (Fedora Forge, Atomic, and Fedora Docs 2026) will continue with full Council backing. Their underlying work will be completed as planned in their current timeboxed state, though the administrative framework around them may evolve. As a second step, we would like to work out a new mechanism to allow Council to set strategic direction in an open, transparent way that more intentionally includes the community voice. We recognise that we have to be better at being more open in our discussions and decision making.
The council is considering the "sandbox" proposal as an alternative or supplement to a process that replaces the Community Initiatives.
Security updates for Thursday
[$] LWN.net Weekly Edition for July 2, 2026
- Front: Xsnow protestware; Git 2.55; Rhombus; kernel hardening; More LSFMM+BPF coverage; 7.2 merge window; Secure Boot certificate expiration; Ceph and Garage; OSPM 2026.
- Briefs: Akrites; Mageia 10; Git 2.55.0; Podman 6.0; systemd v261; Creative Commons chat; Quotes; ...
- Announcements: Newsletters, conferences, security updates, patches, and more.
[$] Secure Boot certificate expiration is here
Linux users who have Secure Boot enabled on their systems rely on certificates issued by Microsoft to verify the software used to boot a system is trusted by the user. One of those certificates expired recently, but that will not cause systems that are able to boot to stop doing so. There are situations where the expiration may cause problems, however, and the window for relying on existing signed binaries is shorter than it might appear. Users and administrators will want to stay on top of these changes. Over the last year, part of my job at Microsoft has been to work on this problem. LWN wrote about the certificate expiration in July 2025, and this article follows up with where we are now.