Quick answer: CVE-2026-98432 is a critical Linux kernel vulnerability (CVSS 9.8) in IPv4 TCP handling that can allow remote root access on some servers. On Nov. 1, 2026, Anza told Solana mainnet-beta validators to act, because Ubuntu had no fixed kernel yet. Interim steps: block TCP packets with IPv4 options and disable Multipath TCP.
A critical Linux kernel vulnerability has put Solana’s validator network on alert. On Nov. 1, 2026, Anza, the team behind the Agave validator client, told mainnet-beta operators to take urgent action against CVE-2026-98432 while Ubuntu’s fix is still in progress.
The bug sits below the validator software, in the operating system itself. As a result, an attacker who exploits it could control the whole machine, not just one app.
What is the CVE-2026-98432 Linux kernel vulnerability?
CVE-2026-98432 is a use-after-free bug in how the kernel sets up IPv4 TCP connections. In simple terms, the kernel can free a block of network-option memory while another task is still using it. The official CVE record was published on Oct. 15, 2026, and the Linux kernel’s CVE authority scored it 9.8, or Critical, under CVSS 3.1. Ubuntu’s tracker rates it High, with a CVSS 4.0 score of 8.3.
The risk became much clearer in late October. Anthropic said its research model built a proof-of-concept exploit that gives a remote attacker root access on Linux servers running a Multipath TCP (MPTCP) listener. No password or user click is needed.
Is anyone exploiting the Linux kernel vulnerability yet?
There are no public reports of attacks so far. The bug was not on the CISA list of known exploited flaws as of Nov. 1, according to a Konfirmity advisory. However, a working proof of concept usually speeds up real attacks.
Why did Anza warn Solana validators?
Anza posted an “URGENT, Critical Linux Kernel Vulnerability, Action Required” alert at 00:07 UTC on Nov. 2 (Nov. 1 in U.S. time). It pointed operators to a thread by Tim Garcia, validator relations lead at the Solana Foundation, who wrote that the bug “is patched in the linux kernel but not yet patched on ubuntu.”
Because of that gap, Solana operators are exposed. Anza’s setup guide says the client runs on Ubuntu 24.04 and needs a public IPv4 address. As The Defiant reported, a host takeover could expose the validator identity key stored on the machine, and a kernel crash could stop block production. The withdrawer key, which controls staked funds, should never live on the server.
How should validators handle the Linux kernel vulnerability now?
Garcia’s guidance gives Ubuntu operators three interim steps:
- Use nftables to block incoming TCP packets that carry IPv4 options.
- Turn off Multipath TCP with
sudo sysctl -w net.mptcp.enabled=0. - Turn off TCP request socket migration with
sudo sysctl -w net.ipv4.tcp_migrate_req=0.
Note that disabling MPTCP stops new sockets but does not close listeners that are already open. AlmaLinux suggests listing them with sudo ss -lnMp and restarting the services that own them.
Do these steps fully fix the bug?
No. These are stopgaps, not a kernel fix. Red Hat warns that filtering reduces exposure but cannot fully block exploitation. The Go Security Team also says the bug is not limited to MPTCP, so servers without MPTCP listeners may face similar attacks. The real fix is a patched kernel followed by a reboot.
Which systems have a fix for the Linux kernel vulnerability?
Upstream stable kernels 5.10.272, 5.15.223, 6.1.190, 6.6.159, 6.12.113, 6.18.56 and 7.2.10 carry the patch. According to cryptonews.net, Red Hat shipped fixes for RHEL 8, 9 and 10 on Nov. 1, while Debian and Amazon Linux list fixed packages. Ubuntu 22.04, 24.04, 26.04 and 26.10 were still marked “Vulnerable, work in progress” on the tracker, last updated Oct. 30.
What does this mean for SOL and crypto markets?
For now, this is an operations risk, not a network outage. Solana kept producing blocks and SOL traded near $94.46 at 09:50 UTC on Nov. 2, down about 1.1% in 24 hours, per CoinGecko. You can follow it on our Solana price page.
The bigger lesson reaches every proof-of-stake chain. Most validators, RPC nodes and exchange hot-wallet servers run Linux, so one kernel bug can touch many networks at once. It also follows recent infrastructure scares, such as the BTCPay Server hot wallet attack. Watch for three signals this week: Ubuntu’s patched kernel, any sign of active exploitation, and whether other chains issue similar alerts.
Not financial advice. This article is for information only. Always do your own research (DYOR) and follow your own security team’s guidance.
Linux Kernel Vulnerability FAQ
Does CVE-2026-98432 affect people holding SOL in a wallet?
Not directly. The bug affects Linux servers, such as validator and RPC hosts. Funds in a hardware or mobile wallet are not exposed by this kernel flaw.
Is Ubuntu 24.04 patched against CVE-2026-98432?
Not yet. As of Nov. 2, 2026, Ubuntu’s tracker listed the main kernel package on 24.04 as vulnerable, with a fix in progress.
Can disabling MPTCP fully protect a server?
No. It lowers risk, but the Go Security Team says the bug is not MPTCP-specific. Operators should install a patched kernel and reboot as soon as one is available.
