CVE-2026-98775
Received Received - Intake

Use-After-Free in Linux Kernel Nitro Enclaves

Publication date: 2026-10-18

Last updated on: 2026-10-18

Assigner: kernel.org

Description
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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Meta Information

Published
2026-10-18
Last Modified
2026-10-18
Generated
2026-10-18
AI Q&A
2026-10-18
EPSS Evaluated
N/A
NVD
CVE-2026-98775
EUVD
EUVD-2026-103860

Affected Vendors & Products

Showing 5 associated CPEs
Vendor Product Version / Range
Linux Linux 9c8eb50fe9e2bb8a2e725979e052fbf592b6b799
Linux Linux 9c8eb50fe9e2bb8a2e725979e052fbf592b6b799
Linux Linux 9c8eb50fe9e2bb8a2e725979e052fbf592b6b799
Linux Linux 9c8eb50fe9e2bb8a2e725979e052fbf592b6b799
Linux Linux 5.10

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a use-after-free vulnerability in the Linux kernel's nitro_enclaves component. It occurs when a specific ioctl operation fails after a file has been created but before it is fully linked to the enclave system. The error path attempts to free the enclave object while a deferred file cleanup operation still references it, leading to a use-after-free condition that can cause system instability or crashes.

Detection Guidance

This vulnerability is specific to the Linux kernel's nitro_enclaves component and requires kernel-level detection. Check if your kernel version includes the vulnerable code path by examining the nitro_enclaves module and looking for SLOT_ALLOC failure scenarios. Use KASAN (Kernel Address Sanitizer) to detect use-after-free errors during enclave operations.

Impact Analysis

This vulnerability could allow an attacker with local access to trigger a kernel crash or memory corruption by exploiting the use-after-free condition. This may lead to denial-of-service attacks or potentially enable privilege escalation if combined with other exploits. Systems using AWS Nitro Enclaves are particularly affected.

Mitigation Strategies

Apply the kernel patch that clears enclave_file->private_data before fput() on the error path. Update to a kernel version that includes the fix for CVE-2026-98775. If immediate patching is not possible, disable the nitro_enclaves module until the fix is applied.

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