CVE-2026-43253

/* * Conceptual Proof of Concept for CVE-2026-43253 * This code simulates the vulnerable condition where a spinlock is held * during a busy-wait loop, causing a soft lockup. * * To test: Load this module in a Linux kernel environment with AMD IOMMU. */ #include <linux/module.h> #include <linux/kernel.h> #include <linux/spinlock.h> #include <linux/delay.h> static DEFINE_SPINLOCK(vuln_lock); static int __init poc_init(void) { unsigned long flags; int i; printk(KERN_INFO "CVE-2026-43253 PoC: Triggering soft lockup simulation...\n"); // Acquire spinlock (disables interrupts) spin_lock_irqsave(&vuln_lock, flags); // Simulate wait_on_sem() busy waiting inside the spinlock // In the real vulnerability, this waits for hardware. // This loop runs for a significant time to trigger the watchdog. for (i = 0; i < 1000000000; i++) { // Busy wait without sleeping or scheduling barrier(); } // Release spinlock (re-enables interrupts) spin_unlock_irqrestore(&vuln_lock, flags); return 0; } static void __exit poc_exit(void) { printk(KERN_INFO "CVE-2026-43253 PoC: Unloaded.\n"); } module_init(poc_init); module_exit(poc_exit); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("PoC for CVE-2026-43253 Soft Lockup");

{"cve": {"id": "CVE-2026-43253", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T12:16:46.033", "lastModified": "2026-05-11T18:40:35.057", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd: move wait_on_sem() out of spinlock\n\nWith iommu.strict=1, the existing completion wait path can cause soft\nlockups under stressed environment, as wait_on_sem() busy-waits under the\nspinlock with interrupts disabled.\n\nMove the completion wait in iommu_completion_wait() out of the spinlock.\nwait_on_sem() only polls the hardware-updated cmd_sem and does not require\niommu->lock, so holding the lock during the busy wait unnecessarily\nincreases contention and extends the time with interrupts disabled."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-667"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.9", "versionEndExcluding": "6.6.128", "matchCriteriaId": "FC8C6130-AEEE-4496-B72F-C7A386E011DC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.75", "matchCriteriaId": "BCE16369-98ED-41CF-8995-DFDC10B288D2"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/496269d12072ecb219826485bdbec70c92a8eef5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/715c263119fd1b918a9fcbd8a36ea5b604a46324", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d2a0cac10597068567d336e85fa3cbdbe8ca62bf", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e15768e68820142077bbca402d8e902f64ade1b0", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/f2f65b28d802a667119147444ec2ae33eebf9a58", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}