CVE-2026-23354
Published: 25 March 2026
Summary
CVE-2026-23354 is a high-severity Improper Validation of Array Index (CWE-129) vulnerability in Linux Linux Kernel. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 3.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and SI-10 (Information Input Validation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Directly mitigates CVE-2026-23354 by requiring timely patching of the Linux kernel flaw in fred_extint() with upstream commits that reposition array_index_nospec() for proper speculative safety.
Addresses the core issue of improper array index validation (CWE-129) by enforcing checks on indices used in kernel array accesses to block speculative execution exploits.
Provides memory protection mechanisms that mitigate speculative execution risks, complementing bounds-checked array accesses in kernel interrupt handling code.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Local kernel flaw (CWE-129) with full C/I/A impact enables direct exploitation for privilege escalation from low-privileged local access.
NVD Description
In the Linux kernel, the following vulnerability has been resolved: x86/fred: Correct speculative safety in fred_extint() array_index_nospec() is no use if the result gets spilled to the stack, as it makes the believed safe-under-speculation value subject to memory predictions. For…
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all practical purposes, this means array_index_nospec() must be used in the expression that accesses the array. As the code currently stands, it's the wrong side of irqentry_enter(), and 'index' is put into %ebp across the function call. Remove the index variable and reposition array_index_nospec(), so it's calculated immediately before the array access.
Deeper analysisAI
CVE-2026-23354 is a vulnerability in the Linux kernel's x86/fred component, specifically within the fred_extint() function. The issue stems from incorrect usage of array_index_nospec() for speculative safety, where the index value is spilled to the stack across an irqentry_enter() call, making it vulnerable to memory predictions. This violates the requirement that array_index_nospec() must be used directly in the array access expression. The flaw is classified under CWE-129 (Improper Validation of Array Index) with a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
A local attacker with low privileges can exploit this vulnerability with low complexity and no user interaction required. Successful exploitation could result in high impacts to confidentiality, integrity, and availability, potentially allowing unauthorized data access, modification, or denial of service through speculative execution leading to improper array indexing.
Mitigation involves applying the upstream kernel patches provided in the referenced stable commits, including 3bc5887b0a2b06d2d9c22f1f4f8500490b3ae643, 92caa5274b99cb6729177232a029ce0dfa6c5f7b, aa280a08e7d8fae58557acc345b36b3dc329d595, and e58f1a9b0677de24dcfee0b21393446ec92ff120, which reposition array_index_nospec() immediately before the array access and remove the intermediate index variable. Security practitioners should update affected Linux kernel installations to versions incorporating these fixes.
Details
- CWE(s)