---
id: "CVE-2026-98793"
kind: "vulnerability"
aliases: ["CVE-2026-98793"]
title: "Linux kernel: invalid NAT type from BPF can corrupt connection tracking"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["bpf", "infrastructure", "linux-kernel", "netfilter"]
not_affected_if: ["no-bpf-nat-programs"]
published_at: "2026-10-18T16:17:33+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:15:13+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98793", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel: invalid NAT type from BPF can corrupt connection tracking

The Linux kernel's netfilter BPF helper bpf_ct_set_nat_info() did not validate the NAT manipulation type before calling nf_nat_setup_info(). A wrong value triggers a kernel warning and can leave a conntrack entry in an inconsistent state that later causes a crash during cleanup.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- unknown

## Fix

- Update the Linux kernel to a release that includes the netfilter: bpf: reject invalid NAT manipulation types fix; the sources do not name the fixed version.

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98793

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

netfilter: bpf: reject invalid NAT manipulation types

As bpf_ct_set_nat_info() is not validating the NAT manipulation type a
wrong value can be passed directly to nf_nat_setup_info(). This triggers
the WARN_ON() at nf_nat_setup_info() and if panic_on_warn isn't set,
then IPS_SRC_NAT_DONE is set without adding nat_bysource and conntrack
cleanup tries to unlink an uninitialized hlist node.

Fix this by checking that NAT manipulation type is correct before
calling nf_nat_setup_info(). In addition, if the WARN_ON is hit, return
NF_DROP instead of continuing with the processing to avoid similar
situations in the future.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_