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Response snapshot Oct 30, 2026, 01:51 UTC

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VulnerabilityCVE-2026-63889

Linux kernel: scsi: scsi_transport_fc: Widen FPIN pname walker counter to u32

In the Linux kernel, the following vulnerability has been resolved: scsi: scsi_transport_fc: Widen FPIN pname walker counter to u32 An adjacent Fibre Channel fabric actor that can deliver an FPIN ELS frame to an lpfc or qla2xxx Linux initiator can trigger a non-return in the generic FC transport.

At a glance

Exploited
Not known
Severity
8.1 High (CVSS 3.1)
Chance of exploitation
0.4% in the next 30 days
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-63889 (opens a new tab)

What happened

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

scsi: scsi_transport_fc: Widen FPIN pname walker counter to u32

An adjacent Fibre Channel fabric actor that can deliver an FPIN ELS frame to an lpfc or qla2xxx Linux initiator can trigger a non-return in the generic FC transport. This is not a local userspace or IP network path; the attacker must be able to inject fabric traffic, for example as a compromised switch or fabric controller, or as a same-zone N_Port on a fabric that permits source spoofing.

The Link-Integrity and Peer-Congestion FPIN walkers used a u8 loop counter against the 32-bit on-wire pname_count field, and did not bound pname_count by the descriptor body already validated by the TLV walker. A pname_count of 256 therefore wraps the counter and keeps the loop condition true indefinitely.

Continue reading

Factor the shared pname_list[] walk into one helper, widen the counter to u32, and clamp pname_count against the entries that fit in the descriptor body before iterating.

Scores and how they were measured

CVSS base severity

8.1

Version 3.1As of

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

0.4%

Scored Percentile 29.6%

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-2026-63889 (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

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-63889, scored 2026-10-29. 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 29). Linux kernel: scsi: scsi_transport_fc: Widen FPIN pname walker counter to u32 (CVE-2026-63889). https://kevwire.com/record/CVE-2026-63889

MLA

"Linux kernel: scsi: scsi_transport_fc: Widen FPIN pname walker counter to u32 (CVE-2026-63889)." KEVWire, 29 Oct. 2026, kevwire.com/record/CVE-2026-63889.

Chicago

KEVWire. "Linux kernel: scsi: scsi_transport_fc: Widen FPIN pname walker counter to u32 (CVE-2026-63889)." Last modified October 29, 2026. https://kevwire.com/record/CVE-2026-63889.

Evidence summary (plain text)

Linux kernel: scsi: scsi_transport_fc: Widen FPIN pname walker counter to u32 (Jul 19, 2026).
In the Linux kernel, the following vulnerability has been resolved:

scsi: scsi_transport_fc: Widen FPIN pname walker counter to u32

An adjacent Fibre Channel fabric actor that can deliver an FPIN ELS
frame to an lpfc or qla2xxx Linux initiator can trigger a non-return in
the generic FC transport. This is not a local userspace or IP network
path; the attacker must be able to inject fabric traffic, for example as
a compromised switch or fabric controller, or as a same-zone N_Port on a
fabric that permits source spoofing.
CVSS 8.1 (version 3.1; evidence as of Oct 29, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-63889).
EPSS 0.4% for the following 30 days, scored Oct 29, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-63889&date=2026-10-29).
Sources:
NVD CVE-2026-63889: https://nvd.nist.gov/vuln/detail/CVE-2026-63889
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-29T19:00:58.773Z&lastModEndDate=2026-10-29T20:30:56.294Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-29T18:31:22.210Z&lastModEndDate=2026-10-29T20:00:56.789Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-29T18:01:00.911Z&lastModEndDate=2026-10-29T19:30:59.315Z&resultsPerPage=500&startIndex=0
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-63889&date=2026-10-29
Record ID: CVE-2026-63889.
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 29, 2026, 20:31 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.

Record JSON

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Record details

Record detail