CVE-2026-46259 procfs: fix missing RCU protection when reading real_parent in do_task_stat()
A use-after-free vulnerability in the Linux kernel's procfs allows attackers to potentially execute code or escalate privileges via improper RCU protection.
- 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-2026-46259?
CVE-2026-46259 is a high-severity use after free vulnerability in Linux kernel, published on 3 Jun 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:
procfs: fix missing RCU protection when reading real_parent in do_task_stat()
When reading /proc/[pid]/stat, do_task_stat() accesses task->real_parent without proper RCU protection, which leads to:
cpu 0 cpu 1 ----- ----- do_task_stat var = task->real_parent release_task call_rcu(delayed_put_task_struct) task_tgid_nr_ns(var) rcu_read_lock <--- Too late to protect task->real_parent! task_pid_ptr <--- UAF! rcu_read_unlock
This patch uses task_ppid_nr_ns() instead of task_tgid_nr_ns() to add proper RCU protection for accessing task->real_parent.
Weakness: CWE-416
Which versions are affected by CVE-2026-46259?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-46259?
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-2026-46259 being exploited?
There is no known exploitation of CVE-2026-46259 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-46259, DEBIAN-CVE-2026-46259, GHSA-vg6r-r7wf-v3q2, ROOT-OS-UBUNTU-2204-CVE-2026-46259, ROOT-OS-UBUNTU-2404-CVE-2026-46259, UBUNTU-CVE-2026-46259.