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Fencer Intel
high 7.8

CVE-2026-63874 json

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

published 3mo ago modified 12d ago also EUVD-2026-45559

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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()

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.

Patch / fix

  • Linux Linux 6.18.36, 7.0.13, 7.1
  • linux Debian 14 7.0.13-1

debian advisories DEBIAN-CVE-2026-63874

  • linux Ubuntu 26.04 LTS 7.0.0-31.31
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1012.12
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1011.11
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1006.7
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1013.13
  • linux-azure Ubuntu 26.04 LTS 7.0.0-1014.14
  • linux-raspi Ubuntu 26.04 LTS 7.0.0-1019.19
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-31.31.1

ubuntu advisories UBUNTU-CVE-2026-63874

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-63874 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-63874 updated

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

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.