---
id: "CVE-2026-98555"
kind: "vulnerability"
aliases: ["CVE-2026-98555"]
title: "Linux kernel LLC: use-after-free and memory leaks on MAC header failure"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "linux-kernel", "networking", "self-hosted"]
not_affected_if: ["kernel-without-llc"]
published_at: "2026-10-18T16:17:07+00:00"
first_seen_at: "2026-10-23T21:57:15+00:00"
updated_at: "2026-10-25T05:23:29+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98555", "first_seen_at": "2026-10-23T21:57:15+00:00"}]
---

# Linux kernel LLC: use-after-free and memory leaks on MAC header failure

In the Linux kernel's LLC (802.2) networking code, an error path frees the wrong socket buffer, leaving a use-after-free and a double free, and in other paths a buffer is leaked. The sources describe memory corruption in the kernel, and the attacker outcome beyond that is not stated.

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

## How to check

- Run `uname -r` and compare the running kernel with the fixed stable release listed by your distribution for CVE-2026-98555
- Check whether the llc module is loaded with `lsmod | grep llc`; unknown whether that is sufficient to be exposed

## Fix

- Install the kernel update from your distribution or the upstream stable branch that includes the llc skb fix for CVE-2026-98555
- Reboot into the patched kernel
- unknown for a specific fixed version, as the sources do not list one

## Timeline

- 2026-10-23T21:57:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98555

## From the sources

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

llc: fix skb UAF and leaks on llc_mac_hdr_init() failure

In llc_conn_ac_resend_i_xxx_x_set_0_or_send_rr(), if llc_mac_hdr_init()
fails, kfree_skb(skb) is called instead of kfree_skb(nskb). This leaks
the newly allocated nskb, reads from the freed skb via LLC_I_GET_NR(pdu),
and double-frees skb when llc_conn_state_process() drops its reference.

In llc_sap_action_send_xid_r() and llc_sap_action_send_test_r(), nskb is
leaked if llc_mac_hdr_init() returns an error.

Free nskb in all three error paths.

---

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