CVE-2026-23354

// Conceptual PoC demonstrating the vulnerability pattern // The issue arises when the sanitized index is spilled to the stack // before the actual array access occurs. #include <linux/kernel.h> #define MAX_ARRAY_SIZE 64 // Simulated vulnerable function pattern based on the CVE description void vulnerable_fred_extint(unsigned long untrusted_user_index) { unsigned long *handler_array; unsigned long index; // 1. Sanitize the index to prevent speculative execution index = array_index_nospec(untrusted_user_index, MAX_ARRAY_SIZE); // 2. FLAW: Function call causes 'index' to be spilled to the stack // The CPU may speculate past this point using the untrusted value // before the memory writeback completes or prediction logic acts. irqentry_enter(); // 3. Access the array using the spilled index // Speculative execution might bypass the protection here handle_interrupt(handler_array[index]); }

{"cve": {"id": "CVE-2026-23354", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-03-25T11:16:33.963", "lastModified": "2026-04-24T19:15:42.007", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/fred: Correct speculative safety in fred_extint()\n\narray_index_nospec() is no use if the result gets spilled to the stack, as\nit makes the believed safe-under-speculation value subject to memory\npredictions.\n\nFor all practical purposes, this means array_index_nospec() must be used in\nthe expression that accesses the array.\n\nAs the code currently stands, it's the wrong side of irqentry_enter(), and\n'index' is put into %ebp across the function call.\n\nRemove the index variable and reposition array_index_nospec(), so it's\ncalculated immediately before the array access."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nx86/fred: Corregir la seguridad especulativa en fred_extint()\n\narray_index_nospec() no sirve de nada si el resultado se vuelca a la pila, ya que hace que el valor considerado seguro bajo especulación esté sujeto a predicciones de memoria.\n\nPara todos los propósitos prácticos, esto significa que array_index_nospec() debe usarse en la expresión que accede al array.\n\nTal como está el código actualmente, está en el lado incorrecto de irqentry_enter(), y 'index' se coloca en %ebp a través de la llamada a la función.\n\nEliminar la variable index y reposicionar array_index_nospec(), para que se calcule inmediatamente antes del acceso al array."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-129"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9.1", "versionEndExcluding": "6.12.77", "matchCriteriaId": "6BF58074-7CF5-43A3-A4ED-82674E37A312"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.17", "matchCriteriaId": "A5E006E4-59C7-43C1-9231-62A72219F2BA"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.7", "matchCriteriaId": "69245D10-0B71-485E-80C3-A64F077004D3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.9:-:*:*:*:*:*:*", "matchCriteriaId": "3F2A4A3D-068A-4CF2-A09F-9C7937DDB0A5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/3bc5887b0a2b06d2d9c22f1f4f8500490b3ae643", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/92caa5274b99cb6729177232a029ce0dfa6c5f7b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/aa280a08e7d8fae58557acc345b36b3dc329d595", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e58f1a9b0677de24dcfee0b21393446ec92ff120", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}