---
id: "CVE-2026-98849"
kind: "vulnerability"
aliases: ["CVE-2026-98849"]
title: "Linux kernel: PFCP driver double-frees its UDP socket on failed registration"
severity: "low"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["kernel", "linux", "runtime", "self-hosted"]
not_affected_if: ["pfcp-module-not-loaded"]
published_at: "2026-10-18T16:17:39+00:00"
first_seen_at: "2026-10-23T21:57:17+00:00"
updated_at: "2026-10-25T05:13:04+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98849", "first_seen_at": "2026-10-23T21:57:17+00:00"}]
---

# Linux kernel: PFCP driver double-frees its UDP socket on failed registration

When creating a pfcp network device fails during registration, the kernel releases the same UDP socket twice, causing a NULL pointer dereference. The sources describe a crash triggered during device creation, and do not describe code execution.

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

## How to check

- Check the running kernel version with `uname -r` and compare it with the fixed kernel named in the advisory.
- Check whether the pfcp module is loaded or available with `lsmod | grep pfcp` or `modinfo pfcp`.

## Fix

- Update the Linux kernel to a release that includes the upstream fix for pfcp socket lifetime (the sources do not name a fixed version).

## Timeline

- 2026-10-23T21:57:17+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98849

## From the sources

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

pfcp: fix socket lifetime on netdevice registration failure

pfcp_newlink() creates the UDP socket before register_netdevice().
If registration fails after pfcp_dev_init() succeeds, the core calls
pfcp_dev_uninit(), which releases the socket and clears pfcp->sk.
The newlink error path then releases it again, causing a NULL pointer
dereference. This was observed with failslab fault injection:

  FAULT_INJECTION: forcing a failure.
  kobject: kobject_add_internal failed for pfcp0 (error: -12 parent: net)
  BUG: KASAN: null-ptr-deref in udp_tunnel_sock_release+0x1c/0x50
  Read of size 8 at addr 0000000000000120 by task ip/1037
  Call trace:
   show_stack+0x18/0x24 (C)
   dump_stack_lvl+0x78/0x90
   print_report+0x468/0x5cc
   kasan_report+0xa4/0xf0
   __asan_load8+0x7c/0xd0
   udp_tunnel_sock_release+0x1c/0x50
   pfcp_newlink+0x128/0x184
   rtnl_newlink+0x848/0xe44
   rtnetlink_rcv_msg+0x468/0x514
   netlink_rcv_skb+0xc0/0x1f0
   rtnetlink_rcv+0x18/0x24
   netlink_unicast+0x4b8/0x558
   netlink_sendmsg+0x2b8/0x584
   ...

Return from pfcp_del_sock() if pfcp->sk is NULL.

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