CVE-2026-89549: Linux Vulnerability (CVSS 7.5)

Description

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().

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.63%

48.2th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= bfd241600a3b0db4fe43c859f1460d0a958d924a, < 9accc25e5af0bac8479f6054e674b2c593c45281; >= bfd241600a3b0db4fe43c859f1460d0a958d924a, < 6f66d38e2a6c78d48723ea17ad86135ec80ca24b; >= bfd241600a3b0db4fe43c859f1460d0a958d924a, < d79d7b9e8acbb53e2d60f6b24afc13e2f15e691f; >= bfd241600a3b0db4fe43c859f1460d0a958d924a, < edb20e8c03aebacb409968c99d046f509c6c485a; >= bfd241600a3b0db4fe43c859f1460d0a958d924a, < 011479cf9a7657d4a3e7cc42a784ac63df594170; >= bfd241600a3b0db4fe43c859f1460d0a958d924a, < 9d04d64ad192439835ed9884d767353061c3ed6f; >= bfd241600a3b0db4fe43c859f1460d0a958d924a, < 8f766d2d0b4dabf54f8b35812df2b4f481d13316; >= bfd241600a3b0db4fe43c859f1460d0a958d924a, < f6310491c4cdb88af73aa551ec9df1f10a90c709
Linux	Linux	2.6.19

References

Timeline

Published: Sep 11, 2026
Last Modified: Sep 14, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-89549?

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().

How severe is CVE-2026-89549?

CVE-2026-89549 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.63% probability of exploitation in the next 30 days.

How do I fix CVE-2026-89549?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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