CVE-2023-53720 net/mlx5e: Release the label when replacing existing ct entry
A memory leak in the Linux kernel mlx5e driver allows local attackers to cause denial of service by exhausting kernel memory.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-53720?
CVE-2023-53720 is a memory corruption vulnerability in Linux, published on 22 Oct 2025. 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:
net/mlx5e: Release the label when replacing existing ct entry
Cited commit doesn't release the label mapping when replacing existing ct entry which leads to following memleak report:
unreferenced object 0xffff8881854cf280 (size 96): comm "kworker/u48:74", pid 23093, jiffies 4296664564 (age 175.944s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<000000002722d368>] __kmalloc+0x4b/0x1c0 [<00000000cc44e18f>] mapping_add+0x6e8/0xc90 [mlx5_core] [<000000003ad942a7>] mlx5_get_label_mapping+0x66/0xe0 [mlx5_core] [<00000000266308ac>] mlx5_tc_ct_entry_create_mod_hdr+0x1c4/0xf50 [mlx5_core] [<000000009a768b4f>] mlx5_tc_ct_entry_add_rule+0x16f/0xaf0 [mlx5_core] [<00000000a178f3e5>] mlx5_tc_ct_block_flow_offload_add+0x10cb/0x1f90 [mlx5_core] [<000000007b46c496>] mlx5_tc_ct_block_flow_offload+0x14a/0x630 [mlx5_core] [<00000000a9a18ac5>] nf_flow_offload_tuple+0x1a3/0x390 [nf_flow_table] [<00000000d0881951>] flow_offload_work_handler+0x257/0xd30 [nf_flow_table] [<000000009e4935a4>] process_one_work+0x7c2/0x13e0 [<00000000f5cd36a7>] worker_thread+0x59d/0xec0 [<00000000baed1daf>] kthread+0x28f/0x330 [<0000000063d282a4>] ret_from_fork+0x1f/0x30
Fix the issue by correctly releasing the label mapping.
Which versions are affected by CVE-2023-53720?
How do I fix CVE-2023-53720?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2023-53720 being exploited?
There is no known exploitation of CVE-2023-53720 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2023-53720, GHSA-2q63-477w-qcv2, UBUNTU-CVE-2023-53720.