CVE-2026-89549
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk48th percentile - higher than 48% of all known CVEs
Summary
In the Linux kernel, svc_pool_for_cpu() can select a pool with no threads when a service runs fewer threads than it has pools (e.g., nfsd in pernode/percpu mode with fewer threads than NUMA nodes). A transport enqueued on such a pool is never picked up, causing the connection to hang indefinitely.
Risk Assessment
This can lead to denial of service (hanging NFS connections) in configurations with limited thread counts. However, it requires a specific NFS server configuration.
Recommendation
Update the Linux kernel to a version containing the fix that skips pools with no threads and falls back to the next populated pool. Check nfsd configurations using pernode/percpu mode.
Other vulnerabilities in Linux kernel
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- CVE-2026-100070Unknown
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: sunrpc: route to a populated pool in svc_pool_for_cpu() svc_set_num_threads() spreads the requested threads evenly across the service's pools (base = nrservs / sv_nrpools). When a service runs fewer threads than it has pools -- e.g. an nfsd configured with fewer threads than the host has NUMA nodes while running in "pernode" or "percpu" mode -- the trailing pools are left with no threads at all. svc_xprt_enqueue() selects a pool from the CPU servicing the transport, queues the transport on that pool's sp_xprts, and only wakes a thread from the same pool. Each thread services exclusively its own pool, so a transport that lands on a threadless pool is enqueued on sp_xprts and never picked up: the connection hangs indefinitely. Have svc_pool_for_cpu() skip pools that currently have no threads, falling back to the next populated pool. This trades NUMA locality for a guarantee that the work is actually serviced. sp_nrthreads is only updated under the service mutex; the lockless read here is a best-effort routing hint, so annotate it with data_race().
Vulnerability data from NVD (NIST) · CISA KEV · EPSS