---
id: "CVE-2026-98775"
kind: "vulnerability"
aliases: ["CVE-2026-98775"]
title: "Linux kernel: nitro enclaves use-after-free when slot allocation fails"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["aws-ec2", "infrastructure", "linux-kernel", "nitro-enclaves"]
not_affected_if: ["nitro-enclaves-driver-not-loaded"]
published_at: "2026-10-18T16:17:31+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:15:28+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98775", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel: nitro enclaves use-after-free when slot allocation fails

A flaw in the Linux kernel's nitro_enclaves driver frees an enclave object and then reads it again when slot allocation fails during VM creation. The sources do not say what an attacker can gain beyond a memory-safety crash and use-after-free.

_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 releases in the upstream commit.
- Check whether the nitro_enclaves driver is loaded with `lsmod | grep nitro_enclaves`.
- Unknown whether the sources list specific affected version ranges.

## Fix

- Update the Linux kernel to a release containing the nitro_enclaves fix (version unknown from the sources).
- Until patched, unknown whether unloading the nitro_enclaves module is a viable workaround.

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98775

## From the sources

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

nitro_enclaves: fix use-after-free on SLOT_ALLOC failure

When ne_create_vm_ioctl() fails the SLOT_ALLOC request after
anon_inode_getfile() has succeeded, the error path calls
fput(enclave_file) and then frees ne_enclave.

In normal userspace context, fput() defers the final __fput() via
task_work. ne_enclave_release() therefore runs after ne_enclave has
already been freed and dereferences ne_enclave->slot_uid, causing a
use-after-free: KASAN: slab-use-after-free in ne_enclave_release.

The enclave has no slot allocated and is not yet linked into the
enclaves list on this error path, so ne_enclave_release() is expected
to return early when slot_uid is zero. However, reading slot_uid
already accesses the freed object.

Clear enclave_file->private_data before fput() on the error path.
ne_enclave_release() then returns immediately when private_data is
NULL, leaving the ioctl error path as the sole owner of ne_enclave.
This is safe because the file has not been fd_install()'d yet.

Tested on an AWS EC2 m5.2xlarge with CONFIG_KASAN=y. Without the
patch, the reproducer triggers a KASAN slab-use-after-free on every
SLOT_ALLOC failure. With the patch, no KASAN report is produced and
the SLOT_ALLOC error is still returned. Normal enclave creation and
teardown are unaffected.

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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_