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#patching

Everything tagged patching, across every stream.

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A researcher finds OpenSSH on musl-based Linux, such as Alpine, accepted any 257+ character password for accounts with no password

An interactive, illustrated history of how a 1980 Unix convention and a 2012 libc change lined up into a login bypass, with a self-check for your own servers.

Özgün Kültekin of the security firm Wakefield published an illustrated write-up (under a pun on "ssh") of a login bypass in OpenSSH on Linux systems built on the musl C library, such as Alpine, OpenWrt, Buildroot and Yocto, when sshd runs without PAM. Locked or key-only accounts are marked with a "" instead of a password hash. Since 2012, musl's crypt() returns "" when it fails, and it fails on passwords over 256 bytes. Because sshd hashes a wrong password even for such accounts, a password of 257 to 1,024 characters produced "*" and matched. He says the flaw has existed since 2016 and that on Alpine's official AWS and Azure images the default user, which has passwordless doas, is affected, which amounts to root.

He says he found it by testing about 17,600 unusual logins across many sshd builds with "agent swarms". OpenSSH 10.6p2, released November 5, works around it in sshd; the OpenSSH team says it considers the root cause outside sshd. The fix is to upgrade or turn off password logins, and his GitHub repo has a check script.

Rabbit Holes 2
  • crypt (C)

    After exploring *ss***e · sshhole.com, to see the function at the center of the bug, read about crypt (C).

    Covers the POSIX C library function used to hash account passwords, whose output string encodes the salt and the hash algorithm.

    Wikipedia · Wade · 5 min

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  • musl

    After exploring *ss***e · sshhole.com, for the library under Alpine and many containers, try musl.

    The entry on musl, the MIT-licensed C standard library for Linux written by Rich Felker as a clean, standards-conformant alternative to glibc.

    Wikipedia · Wade · 5 min

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A developer takes his Ubuntu servers offline because Ubuntu had not shipped a fix for a critical Linux TCP flaw

A short, angry post that sparked a big debate about what 'timely patches' means; the Atlas advisory lays out which distributions had fixes and when.

In a November 2 post, the developer behind chalmovsky.com writes that he took all his Ubuntu servers offline and is moving them to another distribution. His complaint: CVE-2026-98432, a critical (CVSS 9.8) remotely reachable use-after-free in the Linux kernel's TCP code, had been patched by Debian on October 16, and Anthropic says it built a working root exploit, yet more than two weeks later every supported Ubuntu release, LTS included, was listed as vulnerable. He contrasts this with Ubuntu's promise of "timely patches for critical vulnerabilities" and with volunteer-run distributions (Debian, Arch, Alpine) that had shipped the fix.

Atlas's advisory, updated November 5, says Red Hat shipped fixed kernels on November 1 and AlmaLinux on November 2, while Ubuntu had a fixed kernel only for 26.10 and its fixes for 22.04, 24.04 and 26.04 were still in testing. Ubuntu's CVE page rates the bug Critical and offers an interim packet-filtering mitigation.

Rabbit Holes 2
  • Long-term support

    After exploring W*F Ubuntu?, for what an LTS release is supposed to promise, read about Long-term support.

    Explains the product lifecycle policy under which a stable release, such as an Ubuntu LTS, is maintained for longer than the standard edition.

    Wikipedia · Wade · 5 min

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  • Multipath TCP

    After exploring Linux's October 2026 TCP Use-After-Free: CVE-2026-98432 — Atlas, the feature the root exploit relies on is explained in Multipath TCP.

    Multipath TCP is an IETF effort to let a single TCP connection use several network paths at once for more throughput and redundancy.

    Wikipedia · Wade · 5 min

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APT flaw let an attacker on the network slip an unsigned package past Debian and Ubuntu's checks and gain root

Canonical's post explains when the bug is reachable and how switching APT to HTTPS shuts it off.

Canonical has released fixes for CVE-2026-109518, a vulnerability in APT, the package manager used by Debian, Ubuntu and their derivatives, discovered by Max Justicz. An attacker who can tamper with unencrypted HTTP traffic between a machine and its package server, or a malicious mirror, could get APT to install a package that fails signature verification. Since package scripts run as root, that means a full takeover. It is rated High (CVSS 4.0 score 7.7).

The bug needs APT to retry a failed download, which is on by default only in Ubuntu 22.04 and newer; older releases are affected only if retries were enabled. It affects every APT front end but not snaps, and using HTTPS for package sources blocks it. Fixed versions are listed for every Ubuntu release back to 14.04.

Rabbit Holes 2