CVE-2026-98775 nitro_enclaves: fix use-after-free on SLOT_ALLOC failure
A use-after-free in the Linux kernel nitro_enclaves driver allows local attackers to potentially execute code or escalate privileges via a specific ioctl failure path.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98775?
CVE-2026-98775 is an use after free vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-98775?
How do I fix CVE-2026-98775?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-98775 being exploited?
There is no known exploitation of CVE-2026-98775 in the wild and no public exploit code.
Sources
Also known as AZL-109094, BELL-CVE-2026-98775, DEBIAN-CVE-2026-98775, GHSA-8pj3-87fr-9h94, UBUNTU-CVE-2026-98775.