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CVE-2026-43385

In the Linux kernel, the following vulnerability has been resolved: net: Fix rcu_tasks stall in threaded busypoll I was debugging a NIC driver when I noticed that when…

Published May 8, 2026 · corrected/updated Jun 17, 2026 · linux linux kernel · evidence confidence medium

In the Linux kernel, the following vulnerability has been resolved: net: Fix rcu_tasks stall in threaded busypoll I was debugging a NIC driver when I noticed that when I enable threaded busypoll, bpftrace hangs when starting up. dmesg showed: rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 10658 jiffies old. rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 40793 jiffies old. rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 131273 jiffies old. rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 402058 jiffies old. INFO: rcu_tasks detected stalls on tasks: 00000000769f52cd: .N nvcsw: 2/2 holdout: 1 idle_cpu: -1/64 task:napi/eth2-8265 state:R running task stack:0 pid:48300 tgid:48300 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: ? napi_threaded_poll_loop+0x27c/0x2c0 ? __pfx_napi_threaded_poll+0x10/0x10 ? napi_threaded_poll+0x26/0x80 ? kthread+0xfa/0x240 ? __pfx_kthread+0x10/0x10 ? ret_from_fork+0x31/0x50 ? __pfx_kthread+0x10/0x10 ? ret_from_fork_asm+0x1a/0x30 The cause is that in threaded busypoll, the main loop is in napi_threaded_poll rather than napi_threaded_poll_loop, where the latter rarely iterates more than once within its loop. For rcu_softirq_qs_periodic inside napi_threaded_poll_loop to report its qs state, the last_qs must be 100ms behind, and this can't happen because napi_threaded_poll_loop rarely iterates in threaded busypoll, and each time napi_threaded_poll_loop is called last_qs is reset to latest jiffies. This patch changes so that in threaded busypoll, last_qs is saved in the outer napi_threaded_poll, and whether busy_poll_last_qs is NULL indicates whether napi_threaded_poll_loop is called for busypoll. This way last_qs would not reset to latest jiffies on each invocation of napi_threaded_poll_loop.

Grounded briefings

Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.

Executive

CVE-2026-43385 is a high public vulnerability record for linux linux kernel. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.

System administrator

Identify whether linux linux kernel is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: linux/linux kernel; linux/linux kernel (7.0). Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.

Security analyst

Signals on file: CVSS 7.5. It is not currently listed in the CISA Known Exploited catalog. Sources contributing to this record: cve_org, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.

Exploitation and remediation

  • Exploitation evidence

    Not listed as known exploited in CISA KEV. Not in the CISA KEV catalog.

  • Patch and remediation

    No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.

  • Safe detection guidance

    Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 8, 2026 · NIST NVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: net: Fix rcu_tasks stall in threaded busypoll I was debugging a NIC driver when I noticed that when I enable threaded busypoll, bpftrace hangs when starting up. dmesg showed: rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 10658 jiffies old. rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 40

  2. Jun 17, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: net: Fix rcu_tasks stall in threaded busypoll I was debugging a NIC driver when I noticed that when I enable threaded busypoll, bpftrace hangs when starting up. dmesg showed: rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 10658 jiffies old. rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 40

Affected

  • cpe linux/linux kernelversion unspecified
  • cpe linux/linux kernel7.0

Sources

  • CVE.orgVulnerability recordCVE-2026-43385

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2026-43385

    In the Linux kernel, the following vulnerability has been resolved: net: Fix rcu_tasks stall in threaded busypoll I was debugging a NIC driver when I noticed that when I enable threaded busypoll, bpftrace hangs when starting up. dmesg showed: rcu_tasks_wait_gp: rcu_tasks gra

    nvd.nist.gov

References