---
id: "CVE-2026-99222"
kind: "vulnerability"
aliases: ["CVE-2026-99222"]
title: "Linux kernel: key read races module unload, risking freed-memory access"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["kernel", "linux", "runtime", "rxrpc"]
not_affected_if: ["rxrpc-not-loaded"]
published_at: "2026-11-02T16:17:46+00:00"
first_seen_at: "2026-11-02T16:24:05+00:00"
updated_at: "2026-11-02T16:26:58+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99222", "first_seen_at": "2026-11-02T16:24:05+00:00"}]
---

# Linux kernel: key read races module unload, risking freed-memory access

The Linux kernel's keyctl read path checks a key type's read method outside the lock that protects it, so a key can be read while the RxRPC module is being unloaded. The sources describe this as reading freed module memory, which can crash the system or be abused locally.

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

## How to check

- Run `uname -r` and compare against the fixed kernel versions in the upstream stable tree (not stated in the sources)
- Check whether the AF_RXRPC module is loaded with `lsmod | grep rxrpc`

## Timeline

- 2026-11-02T16:24:05+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99222

## From the sources

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

keys: Protect the read method check against type removal

keyctl_read_key() checks key->type->read without holding key->sem.
A reference keeps the key alive, but does not pin the module containing
its type. A surviving RxRPC key can therefore be read while AF_RXRPC
is being unloaded:

  KEYCTL_READ task                    Module unload and key GC
  ----------------                   ------------------------
  lookup_user_key()
  permission / possession checks
  load key->type
                                     af_rxrpc_exit()
                                       unregister_key_type()
                                         GC: down_write(key->sem)
                                         GC: retype to key_type_dead
                                         GC: up_write(key->sem)
                                       unregister_key_type() returns
                                     free_module()
  read saved type's read member

The final access can read freed module storage. The read invocation in
__keyctl_read_key() is already protected by key->sem, but the earlier
method check is outside that critical section.

Move the method check into __keyctl_read_key(), after key_validate() and
under its existing read hold on key->sem. The check and invocation then
use the same protected type for length queries and every read retry.
The GC cannot retype the key until the semaphore is released, and type
unregistration waits for that GC pass before the module can be freed.

Return -EOPNOTSUPP when validation succeeds and the type has no read
method. A temporary buffer may now be allocated before this result;
allocation and copying to userspace remain outside the semaphore.

---

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