CVE-2026-63823 keys: Pin request_key_auth payload in instantiate paths

High 7.8 Published 19 Jul 2026 Updated 19 Oct 2026

A race condition in the Linux kernel key management allows attackers to trigger a use-after-free, potentially leading to code execution or privilege escalation.

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-2026-63823?

CVE-2026-63823 is a high-severity use after free vulnerability in Linux kernel, published on 19 Jul 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:

keys: Pin request_key_auth payload in instantiate paths

A: request_key() B: KEYCTL_INSTANTIATE_IOV ================ =========================

create auth key store rka in auth key wait for helper get auth key load rka from auth key copy user payload sleep on #PF

helper completed detach and free rka destroy auth key wake up use rka->target_key **USE-AFTER-FREE**

Give request_key_auth payloads a refcount. Take a payload reference while authkey->sem stabilizes the payload and revocation state. Hold that reference across the instantiate and reject paths. Drop the auth key owning reference from revoke and destroy.

[jarkko: Replaced the first two paragraphs of text with an actual concurrency scenario.]

Weakness: CWE-416

Which versions are affected by CVE-2026-63823?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-63823?

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-2026-63823 being exploited?

There is no known exploitation of CVE-2026-63823 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2026-63823, DEBIAN-CVE-2026-63823, GHSA-hhf9-cxvj-3mv7, ROOT-OS-DEBIAN-11-CVE-2026-63823, ROOT-OS-UBUNTU-2204-CVE-2026-63823, UBUNTU-CVE-2026-63823.