CVE-2026-93266

Kernel warning via field-spanning challenge copy

Published Sep 24, 2026 · Updated Sep 24, 2026

A field-spanning write in Linux 6.13 allows local users to trigger a kernel FORTIFY warning during RSI attestation token initialization. rsi_attestation_token_init copies a 32-to-64-byte challenge into &regs.a1, so FORTIFY treats the 8-byte a1 field as the whole destination even though the ABI carries the data across a1 through a8. The path is limited to arm64 Realm guests using the arm_cca_guest RSI attestation interface; the published record reports a warning and does not claim memory corruption, privilege gain, or data exposure.

CVSS severityUnavailable
Unscored
EPSS probability0.18%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A field-spanning write in Linux 6.13 allows local users to trigger a kernel FORTIFY warning during RSI attestation token initialization. rsi_attestation_token_init copies a 32-to-64-byte challenge into &regs.a1, so FORTIFY treats the 8-byte a1 field as the whole destination even though the ABI carries the data across a1 through a8. The path is limited to arm64 Realm guests using the arm_cca_guest RSI attestation interface; the published record reports a warning and does not claim memory corruption, privilege gain, or data exposure.

The record

CVE
CVE-2026-93266
Published
Sep 24, 2026
Updated
Sep 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 24, 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=6.13
  2. Affected versionversion=b880a80011f56880f32bde47fc6af313359f926b <221049874b6a78c7d87bc826581b0695cd338e2b
  3. Affected versionversion=b880a80011f56880f32bde47fc6af313359f926b <d29a8ee271da17b5e32d7a76a9c78d43f66447ca
  4. Affected versionversion=b880a80011f56880f32bde47fc6af313359f926b <e505092cb200d430d5b8d8d3e926d45f29474ba3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.13; version=b880a80011f56880f32bde47fc6af313359f926b <221049874b6a78c7d87bc826581b0695cd338e2b; version=b880a80011f56880f32bde47fc6af313359f926b <d29a8ee271da17b5e32d7a76a9c78d43f66447ca; version=b880a80011f56880f32bde47fc6af313359f926b <e505092cb200d430d5b8d8d3e926d45f29474ba3

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)
Vectorlocal
Privilegesauthenticated
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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