CVE-2026-74496
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
In the Linux kernel, the fou_create() function has a use-after-free vulnerability. The fou structure is published via sk_user_data before adding the port to the list, and on error it is freed while still reachable, allowing concurrent reads of freed memory.
Risk Assessment
An attacker could exploit this to gain unauthorized access or cause a system crash, potentially leading to privilege escalation or denial of service.
Recommendation
Apply the kernel patch immediately, which fixes the ordering and uses kfree_rcu() for safe deferred freeing.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: fou: Fix use-after-free in fou_create() fou_create() publishes struct fou through sk_user_data before adding the new FOU port to the per-netns list. If fou_add_to_port_list() fails, the error path frees fou while it is still reachable through sk_user_data. A concurrent receive can then dereference the freed object in fou_from_sock(). This ordering issue was previously noted in the linked discussion. The failure is reachable when local port 0 is requested. Each socket binds to a different ephemeral port, but fou_cfg_cmp() compares the requested port 0 and reports -EALREADY once an entry already exists. Release the tunnel socket before freeing fou so sk_user_data is cleared first, and defer reclamation with kfree_rcu() to protect concurrent RCU readers. This matches the lifetime handling in fou_release().