CVE-2025-71159: linux kernel vulnerability

What is known

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix use-after-free warning in btrfs_get_or_create_delayed_node() Previously, btrfs_get_or_create_delayed_node() set the delayed_node's refcount before acquiring the root->delayed_nodes lock. Commit e8513c012de7 ("btrfs: implement ref_tracker for delayed_nodes") moved refcount_set inside the critical section, which means there is no longer a memory barrier between setting the refcount and setting btrfs_inode->delayed_node. Without that barrier, the stores to node->refs and btrfs_inode->delayed_node may become visible out of order. Another thread can then read btrfs_inode->delayed_node and attempt to increment a refcount that hasn't been set yet, leading to a refcounting bug and a use-after-free warning. The fix is to move refcount_set back to where it was to take advantage of the implicit memory barrier provided by lock acquisition. Because the allocations now happen outside of the lock's critical section, they can use GFP_NOFS instead of GFP_ATOMIC.

Business impact

Successful exploitation of CVE-2025-71159, a critical vulnerability (CVSS 9.8) affecting linux kernel, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.

Recommended administrator action

Confirm whether linux kernel is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.

Sources

• NVD
• Reference
• Reference