CVE-2026-72307 mlxsw: fix refcount leak in mlxsw_sp_vrs_lpm_tree_replace()
A refcount leak in the mlxsw driver allows local attackers to cause memory exhaustion and denial of service.
- 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-2026-72307?
CVE-2026-72307 is a memory corruption vulnerability in Linux, published on 15 Aug 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:
mlxsw: fix refcount leak in mlxsw_sp_vrs_lpm_tree_replace()
When mlxsw_sp_vrs_lpm_tree_replace() fails after replacing some VRs, the error rollback loop does not correctly revert the preceding replacements. The loop decrements the index but fails to update the vr pointer, which still points to the VR that caused the failure. As a result, the condition and the rollback call always operate on the same VR, potentially calling mlxsw_sp_vr_lpm_tree_replace() multiple times on it while never rolling back the earlier VRs. Those VRs continue to hold a reference to new_tree acquired via mlxsw_sp_lpm_tree_hold(), leaking the reference count of new_tree.
Fix by reinitializing vr inside the error loop with the updated index:
vr = &mlxsw_sp->router->vrs[i];
so that the loop correctly iterates over all VRs that were actually replaced.
Which versions are affected by CVE-2026-72307?
How do I fix CVE-2026-72307?
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-2026-72307 being exploited?
There is no known exploitation of CVE-2026-72307 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72307, DEBIAN-CVE-2026-72307, GHSA-7fcx-hvpg-5c9p, UBUNTU-CVE-2026-72307.