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Response snapshot Oct 30, 2026, 17:36 UTC

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VulnerabilityCVE-2026-63874

Linux kernel: net: mctp: usb: fix race between urb completion and rx_retry cancellation

In the Linux kernel, the following vulnerability has been resolved: net: mctp: usb: fix race between urb completion and rx_retry cancellation It's possible that sequencing between setting ->stopped and cancelling the rx_retry work (in ndo_stop) could leave us with an urb queued: T1: ndo_stop T2: rx_retry_work ------------ ---------------- LD: ->stopped => false ST: ->stopped <= true usb_kill_urb() mctp_usb_rx_queue() usb_submit_urb()…

At a glance

Exploited
Not known
Severity
7.8 High (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-63874 (opens a new tab)

What happened

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

net: mctp: usb: fix race between urb completion and rx_retry cancellation

It's possible that sequencing between setting ->stopped and cancelling the rx_retry work (in ndo_stop) could leave us with an urb queued:

T1: ndo_stop T2: rx_retry_work ------------ ---------------- LD: ->stopped => false ST: ->stopped <= true usb_kill_urb() mctp_usb_rx_queue() usb_submit_urb() cancel_delayed_work_sync()

Continue reading

That urb completion can then re-schedule rx_retry_work.

Strenghen the sequencing between the stop (preventing another requeue) and the cancel by updating both atomically under a new rx lock. After setting ->rx_stopped, and cancelling pending work, we know that the requeue cannot occur, so all that's left is killing any pending urb.

Scores and how they were measured

CVSS base severity

7.8

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-63874 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 30). Linux kernel: net: mctp: usb: fix race between urb completion and rx_retry cancellation (CVE-2026-63874). https://kevwire.com/record/CVE-2026-63874

MLA

"Linux kernel: net: mctp: usb: fix race between urb completion and rx_retry cancellation (CVE-2026-63874)." KEVWire, 30 Oct. 2026, kevwire.com/record/CVE-2026-63874.

Chicago

KEVWire. "Linux kernel: net: mctp: usb: fix race between urb completion and rx_retry cancellation (CVE-2026-63874)." Last modified October 30, 2026. https://kevwire.com/record/CVE-2026-63874.

Evidence summary (plain text)

Linux kernel: net: mctp: usb: fix race between urb completion and rx_retry cancellation (Jul 19, 2026).
In the Linux kernel, the following vulnerability has been resolved:

net: mctp: usb: fix race between urb completion and rx_retry cancellation

It's possible that sequencing between setting ->stopped and cancelling
the rx_retry work (in ndo_stop) could leave us with an urb queued:

    T1: ndo_stop                  T2: rx_retry_work
    ------------                  ----------------
                                  LD: ->stopped => false
    ST: ->stopped <= true
    usb_kill_urb()
                                  mctp_usb_rx_queue()
                                    usb_submit_urb()…
CVSS 7.8 (version 3.1; evidence as of Oct 30, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-63874).
Sources:
NVD CVE-2026-63874: https://nvd.nist.gov/vuln/detail/CVE-2026-63874
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T14:50:59.566Z&lastModEndDate=2026-10-30T16:25:56.397Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T13:52:33.301Z&lastModEndDate=2026-10-30T15:50:56.559Z&resultsPerPage=500&startIndex=0
Record ID: CVE-2026-63874.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 30, 2026, 16:25 UTC. Ingestion is not an independent editorial investigation.

NVD status: Analyzed. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

Record detail