---
id: "CVE-2026-99213"
kind: "vulnerability"
aliases: ["CVE-2026-99213"]
title: "Linux kernel vsock: connect and reset race can corrupt memory"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["linux-kernel", "other", "virtualization", "vsock"]
not_affected_if: ["vsock-not-loaded"]
published_at: "2026-10-28T11:17:42+00:00"
first_seen_at: "2026-10-28T11:32:37+00:00"
updated_at: "2026-10-28T11:33:48+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99213", "first_seen_at": "2026-10-28T11:32:37+00:00"}]
---

# Linux kernel vsock: connect and reset race can corrupt memory

In the Linux kernel's vsock code, a reset arriving during connect can remove a socket that is still in the connected table, and a later re-insert can crash the kernel. The sources do not say what an attacker can do beyond the kernel crash and memory corruption.

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

## How to check

- `uname -r` and compare against the kernel release that contains the fix, which the sources do not name
- `lsmod | grep vsock` to see whether vsock modules are loaded at all

## Fix

- Install the patched Linux kernel from your distribution once it ships the upstream fix (the referenced commit 002541ef650b is the supplementary context; the fixed version is unknown from the sources)

## Timeline

- 2026-10-28T11:32:37+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99213

## From the sources

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

vsock: treat TCP_CLOSING as once-established

Handle the TCP_ESTABLISHED -> TCP_CLOSING transition on OP_RST, which can
race with the connect loop. Immediately break and return 0 on
ESTABLISHED/CLOSING. The return value of connect() should reflect what
happened up to the point the connection was established or failed. Events
that occur afterwards must not affect it. E.g. even if OP_RW has already
set sk_err, connect() should still return 0, not ENOBUFS because of it.
Adapt the inaccurate comment above signal_pending().

Resetting a socket that is still present in connected_table can lead to
memory corruption. The reporter noted lost transports for in-flight skbs,
and I have reproduced crashes caused by re-insertion into connected_table.

  list_add double add: new=, prev=, next=.
  kernel BUG at lib/list_debug.c:35!
  Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
  Workqueue: vsock-loopback vsock_loopback_work
  RIP: 0010:__list_add_valid_or_report+0x11f/0x130
  Call Trace:
   vsock_insert_connected.cold+0xe/0x13
   virtio_transport_recv_pkt+0x10e9/0x1460
   vsock_loopback_work+0x305/0x480
   process_one_work+0xe4c/0x1560
   worker_thread+0x4f1/0xd60
   kthread+0x36e/0x470
   ret_from_fork+0x47b/0x6b0
   ret_from_fork_asm+0x1a/0x30

This fix is supplementary to commit 002541ef650b ("vsock: Ignore
signal/timeout on connect() if already established"). Details under Link.

---

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