CVE-2026-98438Hinoki check available

Unspecified impact via uninitialized DATA_FIN checksum

Published Oct 18, 2026 · Updated Oct 18, 2026

Uninitialized checksum use in Linux 7.1 MPTCP allows attackers to cause unspecified impact via data-free DATA_FIN packets. In net/mptcp/options.c, mptcp_write_data_fin creates a DSS mapping without clearing ext->csum after packet initialization stopped zeroing the entire extension structure. The path requires an MPTCP connection with negotiated DSS checksums, which are disabled by default; the public report does not establish disclosure, a crash, or privilege gain.

CVSS severityUnavailable
Unscored
EPSS probability0.14%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Uninitialized checksum use in Linux 7.1 MPTCP allows attackers to cause unspecified impact via data-free DATA_FIN packets. In net/mptcp/options.c, mptcp_write_data_fin creates a DSS mapping without clearing ext->csum after packet initialization stopped zeroing the entire extension structure. The path requires an MPTCP connection with negotiated DSS checksums, which are disabled by default; the public report does not establish disclosure, a crash, or privilege gain.

The record

CVE
CVE-2026-98438
Published
Oct 18, 2026
Updated
Oct 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=7.1
  2. Affected versionversion=cfcceb7a39fc10a6f896af8229bf81d96acb22cc <9a682067dd7b9dce6b94a0a05661dcc921446402
  3. Affected versionversion=cfcceb7a39fc10a6f896af8229bf81d96acb22cc <b110f1dd6cb6a9930503354a01a315e0a821eaa7

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=7.1; version=cfcceb7a39fc10a6f896af8229bf81d96acb22cc <9a682067dd7b9dce6b94a0a05661dcc921446402; version=cfcceb7a39fc10a6f896af8229bf81d96acb22cc <b110f1dd6cb6a9930503354a01a315e0a821eaa7

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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