CVE-2026-99059Network attack vector

Session reuse via stale handshake response acceptance

Published Oct 23, 2026 · Updated Oct 23, 2026

A handshake race in Linux WireGuard allows attackers to recreate an existing session via duplicate responses during handshake reinitiation. In wg_noise_handshake_consume_response(), checking only the state permits an old response to overwrite cryptographic state after a new initiation restores the same state value. The race requires concurrent processing of a valid response twice around a new initiation; upstream describes meaningful practical exploitation as effectively impossible and establishes no further impact.

CVSS severityUnavailable
Unscored
EPSS probability0.51%
Next 30 days · Nov 1, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A handshake race in Linux WireGuard allows attackers to recreate an existing session via duplicate responses during handshake reinitiation. In wg_noise_handshake_consume_response(), checking only the state permits an old response to overwrite cryptographic state after a new initiation restores the same state value. The race requires concurrent processing of a valid response twice around a new initiation; upstream describes meaningful practical exploitation as effectively impossible and establishes no further impact.

The record

CVE
CVE-2026-99059
Published
Oct 23, 2026
Updated
Oct 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 23, 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=e7096c131e5161fa3b8e52a650d7719d2857adfd <3bec3d32c2a3afd164fc87f95457df2cf9049c20
  3. Affected versionversion=e7096c131e5161fa3b8e52a650d7719d2857adfd <4d64a3d6e96aa78619c9c29ffde309794974588a
  4. Affected versionversion=e7096c131e5161fa3b8e52a650d7719d2857adfd <c76a80db593096edf2b3b3972f58b6342a8c6c04
  5. Affected versionversion=e7096c131e5161fa3b8e52a650d7719d2857adfd <d0305f8d90029556260c6824b61c493c424eba9e
  6. Affected versionversion=e7096c131e5161fa3b8e52a650d7719d2857adfd <fb5ce4c7790c3eeec820302d08d70ecf46af4295

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=5.6; version=e7096c131e5161fa3b8e52a650d7719d2857adfd <3bec3d32c2a3afd164fc87f95457df2cf9049c20; version=e7096c131e5161fa3b8e52a650d7719d2857adfd <4d64a3d6e96aa78619c9c29ffde309794974588a; version=e7096c131e5161fa3b8e52a650d7719d2857adfd <c76a80db593096edf2b3b3972f58b6342a8c6c04; version=e7096c131e5161fa3b8e52a650d7719d2857adfd <d0305f8d90029556260c6824b61c493c424eba9e; version=e7096c131e5161fa3b8e52a650d7719d2857adfd <fb5ce4c7790c3eeec820302d08d70ecf46af4295

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)
Vectornetwork
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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