Key facts
- Anthropic said Claude wrote an attack granting full control of a Linux server without a password, using CVE-2026-98432.
- The bug has existed since Linux version 4.4 and scores 9.8 out of 10 for severity, per the report.
- Anthropic said the attack takes less than an hour to find a memory location and five more minutes to run a root command.
- Red Hat released fixes for RHEL 8, 9 and 10 on Sunday, including RHSA-2026:93412.
- Ubuntu's tracker listed every version from 16.04 to 26.10 as vulnerable, with no fix release date given.
Anthropic said its Claude model wrote a working attack that lets a stranger take full control of a Linux server over the internet without a password, exploiting a bug tracked as CVE-2026-98432 that has existed since Linux version 4.4 and scores 9.8 out of 10 for severity. The company described the attack on Oct. 27 in a research post covering five targets: Chrome, Safari, Android, Windows and Linux.
According to Anthropic, Claude wrote the Linux exploit after initial prompting using an unreleased internal model. The attack takes less than an hour to locate a hidden spot in the computer's memory, then five more minutes to run a command with the highest level of access, known as root, the company said.
The flaw is a race condition: one part of the system discards a piece of information while another part is still using it, a mechanics description attributed to AlmaLinux. A specially crafted message that opens an internet connection can trigger it. Anthropic wrote that a lost race only fails the handshake without crashing the system, so an attacker can retry until succeeding.
Anthropic's demonstrated exploit needs a server running multipath TCP, a feature that lets a connection travel over several routes at once and that Go programs have enabled by default since Go 1.24, per the Go Security Team. The Go Security Team said the underlying bug is not specific to that feature.
Red Hat released fixes for RHEL 8, 9 and 10 on Sunday, including RHSA-2026:93412, and published a temporary firewall rule that it said reduces exposure but cannot fully prevent it, with a full solution still under development. Debian, SUSE, Oracle Linux and Amazon Linux have also shipped fixes for at least some versions, the report said. Ubuntu's tracker listed every version from 16.04 to 26.10 as vulnerable, with fixes in progress for 22.04, 24.04, 26.04 and 26.10 and no release date given. The Go Security Team said the best fix is to upgrade to a patched kernel.