CVE-2026-89667
UnknownSummary
In the Linux kernel, a race condition exists in the nfsd module between the shrinker, GC worker, and fsnotify/lease callbacks versus per-net shutdown in the filecache. An nfsd_file can be unhashed and moved to the dispose list before nfsd_file_cache_shutdown_net() processes it, causing a leak of the file and its associated state. The fix widens the nfsd_gc_lock scope across all three callers of nfsd_file_dispose_list_delayed() and adds a spinlock barrier in the per-net shutdown function.
Risk Assessment
Kernel resource leaks (nfsd_file objects and associated state) can lead to gradual memory exhaustion and system instability, especially on long-running NFS servers. Environments with frequent network connection creation and teardown may experience accelerated impact.
Recommendation
Update the Linux kernel to a version containing the fix for CVE-2026-89667. If immediate patching is not possible, consider limiting NFS service exposure and monitoring kernel memory usage on NFS server hosts.
Other vulnerabilities in Linux kernel (nfsd)
See all- CVE-2026-89706Unknown
In the Linux kernel, the nfsd module failed to reset the write verifier when an async COPY writeback failed. When writeback failed, the server reported NFS_UNSTABLE to the NFS client but did not rotate the verifier, so after COMMIT the client treated the data as durable even though the write had failed.
- CVE-2026-89705Unknown
In the Linux kernel, nfsd_dispatch() did not restore rq_status_counter to an even value on all exit paths (cache-hit, drop, encode-error). The counter left odd caused the lockless reader in nfsd_nl_rpc_status_get_dumpit() to treat rqstp fields as stable and read past the end of the 8-element ops array.
- CVE-2026-89704Unknown
In the Linux kernel, _nfsd_copy_file_range() sampled the writeback error cursor (dst->f_wb_err) after the copy loop instead of before it. Concurrent COMMIT or stable WRITE could advance the cursor, so the writeback error went undetected and NFSD4_COPY_F_COMMITTED was set despite the failed write.
- CVE-2026-89703Unknown
In the Linux kernel, nfsd4_drop_revoked_stid(), which handles FREE_STATEID for admin-revoked delegations, did not set SC_STATUS_FREED before releasing cl_lock. Without this flag the freed delegation was added to cl_revoked, causing a use-after-free when that list is later traversed in __destroy_client().
- CVE-2026-89701Unknown
In the Linux kernel, the xdrgen-based TIME_DELEG_ACCESS and TIME_DELEG_MODIFY decode arms stored a raw uint32_t nseconds directly into tv_nsec without enforcing nseconds < NSEC_PER_SEC. A malicious client could send a malformed timespec that propagated through notify_change() to disk.
- CVE-2026-89700Unknown
In the Linux kernel, the nfsd_sock_nl_policy declared NFSD_A_SOCK_ADDR as a bare NLA_BINARY attribute with no minimum length. A CAP_NET_ADMIN caller could send a 16-byte address with sa_family=AF_INET6, causing a 12-byte out-of-bounds read across three consumers (rpc_cmp_addr_port, svc_find_listener, kernel_bind).
- CVE-2026-89699Unknown
In the Linux kernel, nfsd4_decode_create() accepted an unbounded cr_datalen from the wire for NF4LNK symlink targets, allowing a client to force a kmalloc of up to the maximum RPC payload size (several MiB) per COMPOUND op. The VFS rejected oversized targets with ENAMETOOLONG, but the allocation had already occurred.
- CVE-2026-89698Unknown
In the Linux kernel, struct nfsd_genl_rqstp declared rq_daddr and rq_saddr as plain struct sockaddr (16 bytes). With an IPv6 NFS client connected, nfsd_genl_rpc_status_compose_msg() cast these fields to struct sockaddr_in6 (28 bytes), reading 8 bytes past the field and shipping a truncated IPv6 address plus part of rq_flags to userspace via netlink.
- CVE-2026-89697Unknown
In the Linux kernel, the BOTH_TIME_SET branch in nfsd_proc_setattr() called fh_verify() early so setattr_prepare() could inspect the dentry. This caused nfsd_setattr() to skip fh_want_write(), so notify_change() ran without a mount write reference.
- CVE-2026-89696Unknown
In the Linux kernel's nfsd module, a flaw allows subsequent operations to run after a FOREIGN PUTFH even when fh_dentry is NULL. A remote NFSv4.2 client can craft a COMPOUND request that triggers a NULL pointer dereference in the nfsd kernel thread. The issue affects configurations with CONFIG_NFSD_V4_2_INTER_SSC enabled.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: nfsd: close shrinker/GC/fsnotify vs per-net shutdown race in filecache The shrinker, GC worker, and fsnotify/lease callbacks can unhash an nfsd_file from the rhashtable and then call nfsd_file_dispose_list_delayed() to move it to the per-net dispose list. If nfsd_file_cache_shutdown_net() runs concurrently, its rhashtable walk misses the already-unhashed file, and its drain of the per-net dispose list can run before the file has been queued. The file then sits on the per-net list with no thread to drain it, leaking both the file and its associated state. The GC worker and shrinker already hold nfsd_gc_lock while walking the LRU, but in the original code they release it before calling nfsd_file_dispose_list_delayed(). The fsnotify/lease path (nfsd_file_close_inode) has no synchronization at all. Fix this by: 1. Widening nfsd_gc_lock in both nfsd_file_gc() and nfsd_file_lru_scan() to cover the nfsd_file_dispose_list_delayed() call. 2. Wrapping nfsd_file_close_inode() in nfsd_gc_lock so that all three callers of nfsd_file_dispose_list_delayed() hold the lock. 3. Adding a spin_lock/unlock(nfsd_gc_lock) barrier in nfsd_file_cache_shutdown_net() after the purge, so that any in-progress disposal has fully completed before the per-net list is drained. All operations inside the lock are non-sleeping (rhashtable lookups, atomic bit/refcount ops, list moves, svc_wake_up), so the spinlock is appropriate.