CVE-2026-68450 btrfs: free mapping node on duplicate reloc root insert
A memory leak in the Linux kernel btrfs filesystem occurs when a duplicate reloc root insert fails, potentially leading to resource exhaustion and denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68450?
CVE-2026-68450 is a memory corruption vulnerability in Linux, published on 12 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:
btrfs: free mapping node on duplicate reloc root insert
__add_reloc_root() allocates a mapping_node before inserting it into rc->reloc_root_tree. If rb_simple_insert() finds an existing entry, it returns the existing rb_node and leaves the newly allocated node unlinked.
The error path then returns -EEXIST without freeing the new node. Since the node was never inserted into reloc_root_tree, the later cleanup in put_reloc_control() cannot find it either.
Free the newly allocated node before returning -EEXIST.
The callers currently assert that -EEXIST should not happen, so this is a defensive cleanup for an unexpected duplicate insert path. If the path is ever reached, the local allocation should still be released.
Which versions are affected by CVE-2026-68450?
How do I fix CVE-2026-68450?
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-2026-68450 being exploited?
There is no known exploitation of CVE-2026-68450 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68450, DEBIAN-CVE-2026-68450, GHSA-mmwm-g85r-pjj6, UBUNTU-CVE-2026-68450.