CVE-2026-93266
Received Received - Intake

Heap-based Buffer Overflow in Linux Kernel RSI Attestation Token

Publication date: 2026-09-24

Last updated on: 2026-09-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: arm64: RSI: fix field-spanning write warning in attestation token init The challenge is passed in registers a1 through a8. However, copying to &regs.a1 makes FORTIFY treat the destination as the single a1 field, resulting in a field-spanning write warning. [1] Overlay the SMCCC register structure with an RSI-specific argument layout and copy the challenge into an explicit 64-byte array. This keeps the existing a1-a8 argument encoding while giving the copy a correctly sized destination object. [1] memcpy: detected field-spanning write (size 64) of single field "&regs.a1" at ./arch/arm64/include/asm/rsi_cmds.h:119 (size 8) WARNING: ./arch/arm64/include/asm/rsi_cmds.h:119 at rsi_attestation_token_init+0xdc/0xf8 [arm_cca_guest], CPU#0: cat/3314

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Meta Information

Published
2026-09-24
Last Modified
2026-09-24
Generated
2026-09-25
AI Q&A
2026-09-24
EPSS Evaluated
N/A
NVD
CVE-2026-93266
EUVD
EUVD-2026-86138

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability where a field-spanning write warning occurs during attestation token initialization. The issue happens when copying a challenge passed in registers a1 through a8 into a structure field. FORTIFY detects this as writing 64 bytes to a single 8-byte field (&regs.a1), triggering a warning in the RSI attestation token init process.

Detection Guidance

This vulnerability is specific to the Linux kernel's arm64 architecture and RSI attestation token handling. Detection requires checking kernel logs for field-spanning write warnings related to rsi_attestation_token_init. Look for messages like 'memcpy: detected field-spanning write' in system logs or dmesg output.

Impact Analysis

This vulnerability may cause kernel warnings or errors during attestation token initialization in arm64 systems using RSI. While not a direct security flaw, it could lead to system instability or unexpected behavior in secure environments relying on attestation mechanisms.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA as it is a low-level kernel memory handling issue in the Linux RSI attestation token initialization. There is no evidence it impacts data protection, privacy, or security controls required by these regulations.

Mitigation Strategies

Apply the kernel patch that resolves this issue. Update your Linux kernel to a version containing the fix for arm64 RSI attestation token initialization. Monitor kernel logs after update to confirm the warning no longer appears.

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