CVE-2026-80587Network attack vectorHinoki check available

Remote connection-state corruption via conflicting MPTCP suboptions

Published Aug 26, 2026 · Updated Aug 27, 2026

Improper MPTCP option validation in affected Linux kernel branches allows remote attackers to corrupt connection state via crafted suboptions. The incoming-option parser accepts mutually exclusive or repeated suboptions and lets later fields overwrite earlier MPTCP state instead of ignoring each conflicting extra option. A remote TCP peer reaching an MPTCP socket needs no account or user interaction and can expose data, corrupt the reassembled byte stream, reset connections, or trigger a kernel panic.

CVSS severity9.8
Critical
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Improper MPTCP option validation in affected Linux kernel branches allows remote attackers to corrupt connection state via crafted suboptions. The incoming-option parser accepts mutually exclusive or repeated suboptions and lets later fields overwrite earlier MPTCP state instead of ignoring each conflicting extra option. A remote TCP peer reaching an MPTCP socket needs no account or user interaction and can expose data, corrupt the reassembled byte stream, reset connections, or trigger a kernel panic.

The record

CVE
CVE-2026-80587
Published
Aug 26, 2026
Updated
Aug 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-1288, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=5.6
  2. Affected versionversion=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <099bfcbd0c16ae9b50aba2a1bea033e63f895da7
  3. Affected versionversion=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <0e2210af439755a2af352eea4178261dcf61742e
  4. Affected versionversion=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <6bab907292155513af397a12ccb488acbfc30d79
  5. Affected versionversion=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <a04dcc784959e4702048785d87e0d029bd2fbdcb
  6. Affected versionversion=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <b6ee361524641f57b2e2363f7737f20e17f67827
  7. Affected versionversion=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <dc1d8d3eb345c616fbe922a010fa391c72c54d52

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.6; version=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <099bfcbd0c16ae9b50aba2a1bea033e63f895da7; version=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <0e2210af439755a2af352eea4178261dcf61742e; version=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <6bab907292155513af397a12ccb488acbfc30d79; version=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <a04dcc784959e4702048785d87e0d029bd2fbdcb; version=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <b6ee361524641f57b2e2363f7737f20e17f67827; version=eda7acddf8080bb2d022a8d4b8b2345eb80c63ec <dc1d8d3eb345c616fbe922a010fa391c72c54d52

Published CVSS scores

9.8Linux kernel CVE teamCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

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

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1288Improper Validation of Consistency within Input
T1210Exploitation of Remote Services

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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