CVE-2026-89714

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails

nfs4_server_common_setup() allocates server->delegation_hash_table

first, but server->destroy - the only path that frees the table via

nfs4_destroy_server() - is not assigned until the very end of the

function. If any intermediate step fails (the is_ds_only_client()

check, nfs4_init_session(), nfs4_get_rootfh(), or nfs_probe_server()),

the function returns with server->destroy still NULL, so the caller's

nfs_free_server() skips the destroy callback and the hash table is

leaked (4 KiB per attempt with the default delegation watermark).

This is trivially reachable from userspace: every failed NFSv4 mount

leaks one allocation. A client that persistently retries a mount that

cannot succeed leaks kernel memory without bound. Observed in

production where a Longhorn backup poller retried mount.nfs4 against

an NFSv3-only server roughly 10 times per se

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References