CVE-2026-80586Network attack vector

Unauthenticated kernel memory corruption via stale DSS fields

Published Aug 26, 2026 · Updated Aug 27, 2026

Uninitialized-data access in the Linux MPTCP option parser allows remote attackers to corrupt kernel networking state via malformed DSS options. After rejecting a size-invalid DSS suboption, net/mptcp/options.c leaves use_ack, use_map, dsn64, and data_fin set while related values remain uninitialized, so later acknowledgment and mapping paths consume stale stack data. Reachability requires an MPTCP session to a host with CONFIG_MPTCP enabled; consequences include kernel-memory disclosure, altered or truncated data delivery, connection hangs, or a kernel panic when panic_on_warn is set.

CVSS severity9.8
Critical
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uninitialized-data access in the Linux MPTCP option parser allows remote attackers to corrupt kernel networking state via malformed DSS options. After rejecting a size-invalid DSS suboption, net/mptcp/options.c leaves use_ack, use_map, dsn64, and data_fin set while related values remain uninitialized, so later acknowledgment and mapping paths consume stale stack data. Reachability requires an MPTCP session to a host with CONFIG_MPTCP enabled; consequences include kernel-memory disclosure, altered or truncated data delivery, connection hangs, or a kernel panic when panic_on_warn is set.

The record

CVE
CVE-2026-80586
Published
Aug 26, 2026
Updated
Aug 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-824
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

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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=5.6
  2. Affected versionversion=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <15e35fdad7a5576bf3f1c8d688877aeb5d1b506b
  3. Affected versionversion=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <192878df582c51d440bf7b91a15f297f29f2b596
  4. Affected versionversion=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <1fade1b2ac5b1a4948e538fae7313bea57b5ac36
  5. Affected versionversion=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <26dac5c9ffb20812b475fdf253eb04fab99cff3b
  6. Affected versionversion=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <27ed642a4e7e4b5df4b8522c72c457a67e052493
  7. Affected versionversion=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <35772b4981f38ba8059372cde8753e8e477e98ec
  8. Affected versionversion=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <4e80eff5c1c893aca2ac1d202f0b256d2e52ecde
  9. Affected versionversion=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <b1256090816ec46011601e084be580731df58fc7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.6; version=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <15e35fdad7a5576bf3f1c8d688877aeb5d1b506b; version=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <192878df582c51d440bf7b91a15f297f29f2b596; version=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <1fade1b2ac5b1a4948e538fae7313bea57b5ac36; version=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <26dac5c9ffb20812b475fdf253eb04fab99cff3b; version=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <27ed642a4e7e4b5df4b8522c72c457a67e052493; version=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <35772b4981f38ba8059372cde8753e8e477e98ec; version=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <4e80eff5c1c893aca2ac1d202f0b256d2e52ecde; version=648ef4b88673dadb8463bf0d4b10fbf33d55def8 <b1256090816ec46011601e084be580731df58fc7

Published CVSS scores

7.0Red HatCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
9.8Linux 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.

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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-824Access of Uninitialized Pointer

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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