CVE-2025-38209 nvme-tcp: remove tag set when second admin queue config fails
A use-after-free in the Linux kernel NVMe-TCP driver allows attackers to cause a system crash or potentially execute code via crafted network traffic.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38209?
CVE-2025-38209 is a critical use after free vulnerability in Linux kernel, published on 4 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
nvme-tcp: remove tag set when second admin queue config fails
Commit 104d0e2f6222 ("nvme-fabrics: reset admin connection for secure concatenation") modified nvme_tcp_setup_ctrl() to call nvme_tcp_configure_admin_queue() twice. The first call prepares for DH-CHAP negotitation, and the second call is required for secure concatenation. However, this change triggered BUG KASAN slab-use-after- free in blk_mq_queue_tag_busy_iter(). This BUG can be recreated by repeating the blktests test case nvme/063 a few times [1].
When the BUG happens, nvme_tcp_create_ctrl() fails in the call chain below:
nvme_tcp_create_ctrl() nvme_tcp_alloc_ctrl() new=true ... Alloc nvme_tcp_ctrl and admin_tag_set nvme_tcp_setup_ctrl() new=true nvme_tcp_configure_admin_queue() new=true ... Succeed nvme_alloc_admin_tag_set() ... Alloc the tag set for admin_tag_set nvme_stop_keep_alive() nvme_tcp_teardown_admin_queue() remove=false nvme_tcp_configure_admin_queue() new=false nvme_tcp_alloc_admin_queue() ... Fail, but do not call nvme_remove_admin_tag_set() nvme_uninit_ctrl() nvme_put_ctrl() ... Free up the nvme_tcp_ctrl and admin_tag_set
The first call of nvme_tcp_configure_admin_queue() succeeds with new=true argument. The second call fails with new=false argument. This second call does not call nvme_remove_admin_tag_set() on failure, due to the new=false argument. Then the admin tag set is not removed. However, nvme_tcp_create_ctrl() assumes that nvme_tcp_setup_ctrl() would call nvme_remove_admin_tag_set(). Then it frees up struct nvme_tcp_ctrl which has admin_tag_set field. Later on, the timeout handler accesses the admin_tag_set field and causes the BUG KASAN slab-use-after-free.
To not leave the admin tag set, call nvme_remove_admin_tag_set() when the second nvme_tcp_configure_admin_queue() call fails. Do not return from nvme_tcp_setup_ctrl() on failure. Instead, jump to "destroy_admin" go-to label to call nvme_tcp_teardown_admin_queue() which calls nvme_remove_admin_tag_set().
Weakness: CWE-416
Which versions are affected by CVE-2025-38209?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-38209?
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-2025-38209 being exploited?
There is no known exploitation of CVE-2025-38209 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-38209, GHSA-w8w5-45x4-qwqp, UBUNTU-CVE-2025-38209.