Science & Tech · Cybersecurity · 18 hrs ago
Critical Linux flaw can allow remote code execution
A critical flaw in Linux's IPv4 TCP code can let attackers run code remotely without logging in.
The vulnerability affects kernels dating back to version 4.4 and is tracked as CVE-2026-98432.
It occurs when a timing error causes the kernel to access memory that has already been freed while handling connection requests.
Red Hat has released fixed kernels for RHEL 8, 9 and 10, and systems need a reboot after the update is installed.
Ubuntu's fixes for versions 22.04, 24.04 and 26.04 remain in an opt-in testing channel, with no date announced for general release.
Older Ubuntu versions listed in the notice do not yet have fixes.
The flaw is rated 9.8 out of 10, making it a serious risk for systems exposed to network connections.
Administrators can check their kernel version and install available fixes; Canonical says it is testing updates before moving them to its regular channel.
A Linux kernel flaw tracked as CVE-2026-98432 can allow remote code execution by an unauthenticated attacker.
The vulnerability is a use-after-free in the kernel’s IPv4 TCP networking code and has a kernel-team severity score of 9.8 out of 10.
Red Hat has released fixed kernels for Enterprise Linux 8, 9 and 10, while Ubuntu fixes for versions 22.04, 24.04 and 26.04 remain in an opt-in testing channel.
The flaw has been present since Linux kernel version 4.4, and an upstream fix landed in October.
Researchers at Anthropic demonstrated an AI model bypassing kernel address space layout randomization and executing commands as root within 53 minutes.
- Who
- The Linux kernel team, Red Hat, Canonical and researchers at Anthropic are among those involved.
- What
- CVE-2026-98432 is a Linux kernel use-after-free flaw that can enable remote code execution without authentication.
- When
- The upstream fix landed in October 2026. Red Hat shipped fixes on November 1, and Canonical said on November 2 that Ubuntu fixes were in testing.
- Where
- The flaw affects the Linux kernel’s IPv4 TCP networking code and systems using affected Linux distributions.
- Why
- A race during TCP connection requests can cause the kernel to read memory that has already been freed.
This story does not have two clearly opposing sides.
The upstream fix for the vulnerability landed.
Red Hat published an nftables rule intended to block the known trigger for the race.
Red Hat shipped fixed kernels for Enterprise Linux 8, 9 and 10.
Canonical said Ubuntu fixes for versions 22.04, 24.04 and 26.04 were in its opt-in testing channel.
- CVE
- CVE-2026-98432
- Kernel severity score
- 9.8 out of 10
- Affected kernel history
- Present since Linux version 4.4
- Red Hat fixes
- Enterprise Linux 8, 9 and 10
- Ubuntu fixes in testing
- 22.04 LTS, 24.04 LTS and 26.04 LTS
- Anthropic demonstration
- AI model executed commands as root within 53 minutes