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Response snapshot Oct 27, 2026, 14:00 UTC

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VulnerabilityCVE-2026-63919

Linux kernel: xfrm: input: hold netns during deferred transport reinjection

In the Linux kernel, the following vulnerability has been resolved: xfrm: input: hold netns during deferred transport reinjection Transport-mode reinjection stores a struct net pointer in skb->cb and uses it later from xfrm_trans_reinject().

At a glance

Exploited
Not known
Severity
8.8 High (CVSS 3.1)
Chance of exploitation
0.7% in the next 30 days
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-63919 (opens a new tab)

What happened

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

xfrm: input: hold netns during deferred transport reinjection

Transport-mode reinjection stores a struct net pointer in skb->cb and uses it later from xfrm_trans_reinject(). That pointer must stay valid until the deferred callback runs.

Take a netns reference when queueing deferred reinjection work and drop it after the callback completes. Use maybe_get_net() so the queueing path does not revive a namespace that is already being torn down.

Continue reading

This keeps the existing workqueue design and fixes the netns lifetime handling in one place for all users of xfrm_trans_queue_net().

Scores and how they were measured

CVSS base severity

8.8

Version 3.1As of

CVSS:3.1/AV:N/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

0.7%

Scored Percentile 50.9%

Model and measurement source (opens a new tab)

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-2026-63919 (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

  4. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-63919, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

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

APA

KEVWire. (2026, October 27). Linux kernel: xfrm: input: hold netns during deferred transport reinjection (CVE-2026-63919). https://kevwire.com/record/CVE-2026-63919

MLA

"Linux kernel: xfrm: input: hold netns during deferred transport reinjection (CVE-2026-63919)." KEVWire, 27 Oct. 2026, kevwire.com/record/CVE-2026-63919.

Chicago

KEVWire. "Linux kernel: xfrm: input: hold netns during deferred transport reinjection (CVE-2026-63919)." Last modified October 27, 2026. https://kevwire.com/record/CVE-2026-63919.

Evidence summary (plain text)

Linux kernel: xfrm: input: hold netns during deferred transport reinjection (Jul 19, 2026).
In the Linux kernel, the following vulnerability has been resolved:

xfrm: input: hold netns during deferred transport reinjection

Transport-mode reinjection stores a struct net pointer in skb->cb and
uses it later from xfrm_trans_reinject(). That pointer must stay valid
until the deferred callback runs.

Take a netns reference when queueing deferred reinjection work and drop
it after the callback completes. Use maybe_get_net() so the queueing
path does not revive a namespace that is already being torn down.

This keeps the existing workqueue design and fixes the netns lifetime
handling in one place for all users of xfrm_trans_queue_net().
CVSS 8.8 (version 3.1; evidence as of Oct 27, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-63919).
EPSS 0.7% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-63919&date=2026-10-26).
Sources:
NVD CVE-2026-63919: https://nvd.nist.gov/vuln/detail/CVE-2026-63919
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-27T12:21:00.901Z&lastModEndDate=2026-10-27T13:50:56.135Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-27T11:51:11.314Z&lastModEndDate=2026-10-27T13:20:57.536Z&resultsPerPage=500&startIndex=0
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-63919&date=2026-10-26
Record ID: CVE-2026-63919.
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 27, 2026, 13:46 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