Solana validators have been urged to secure their servers against a critical Linux vulnerability that Ubuntu has yet to patch.
Anza, a Solana-focused software developer, issued an urgent warning to mainnet-beta validators on Nov. 1, calling for immediate action against CVE-2026-98432, a vulnerability that could allow hackers to remotely take control of affected Linux servers.
Tim Garcia, validator relations lead at the Solana Foundation, said the underlying flaw had already been fixed in the Linux kernel but remained unpatched in Ubuntu, an operating system commonly used by Solana validators.
He stated:
“Validators! CVE-2026-98432 is patched in the linux kernel but not yet patched on ubuntu.”
He advised affected operators to block incoming TCP packets containing IPv4 options, disable Multipath TCP (MPTCP), and turn off TCP request-socket migration until a security update becomes available.
The warning places Solana's validator infrastructure among systems potentially exposed to a vulnerability with a critical severity score of 9.8 out of 10.
Researchers demonstrate remote server takeover as Ubuntu fix lags
The flaw stems from a memory-handling error during IPv4 TCP connection processing that can allow attackers to exploit a race condition without authentication or user interaction.
In research published Oct. 27, Anthropic disclosed that an unreleased Claude research model developed an exploit capable of executing commands with root privileges on Linux servers running an MPTCP listener.
The attack involved leaking kernel memory information before manipulating the system into executing malicious commands. Anthropic said its demonstration took approximately 53 minutes to achieve remote command execution.
Such access could give attackers control over an affected server, potentially compromising a validator's operations and sensitive credentials stored on the machine.
However, the demonstrated exploit involved a specific MPTCP configuration. No evidence shows Solana validators have been compromised through the flaw, and the research does not establish that every validator is vulnerable to the demonstrated attack.
The Ubuntu security tracker still listed its main Linux kernel package for Ubuntu 24.04 as “Vulnerable work in progress” as of Nov. 2, identifying version 6.8.0-149.149 as the planned fix.
That leaves affected operators dependent on temporary protections, although Red Hat warned that blocking malicious IPv4 traffic cannot completely eliminate exposure and could interfere with some workloads.
Other Linux distributions have moved ahead. Amazon Web Services confirmed that corrected kernel packages were available for Amazon Linux 2 and Amazon Linux 2023, and instructed operators to update and reboot their servers.
Anza's validator requirements specify Ubuntu 24.04 and public IPv4 connectivity, although actual exposure depends on each server's kernel version and network configuration.
The remaining uncertainty is how many Solana validators are running affected configurations. Ubuntu operators also face an outstanding remediation step: installing the corrected kernel once published and confirming that their servers are running it after a reboot.
