CVE-2026-31471

/* * Conceptual PoC for CVE-2026-31471 * This PoC demonstrates the logic flaw where a failed allocation * leads to a dangling pointer in x->mode_data. * Triggering this requires local access and ability to manipulate * xfrm states and memory pressure. */ #include <stdio.h> #include <stdlib.h> #include <string.h> // Simulating the kernel structure behavior struct xfrm_state { void *mode_data; }; struct iptfs_state { int data; }; // Simulating the vulnerable function logic int vulnerable_iptfs_clone_state(struct xfrm_state *x) { struct iptfs_state *new_iptfs = malloc(sizeof(struct iptfs_state)); x->mode_data = new_iptfs; // 1. Store pointer before full setup // Simulate allocation failure for reorder window void *reorder_window = malloc(1024 * 1024 * 100); // Large alloc to fail easily if (!reorder_window) { free(new_iptfs); // 2. Free the state return -1; // 3. Return error, x->mode_data is now dangling } return 0; } void simulate_destroy_state(struct xfrm_state *x) { printf("Destroying state via mode_data: %p\n", x->mode_data); if (x->mode_data) { free(x->mode_data); // 4. Double Free / UAF occurs here printf("Double free triggered!\n"); } } int main() { struct xfrm_state x = {0}; printf("Triggering vulnerable clone path...\n"); int ret = vulnerable_iptfs_clone_state(&x); if (ret != 0) { printf("Clone failed (expected), unwinding...\n"); simulate_destroy_state(&x); // Trigger the vulnerability } return 0; }

{"cve": {"id": "CVE-2026-31471", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:43.610", "lastModified": "2026-05-06T21:37:47.057", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: iptfs: only publish mode_data after clone setup\n\niptfs_clone_state() stores x->mode_data before allocating the reorder\nwindow. If that allocation fails, the code frees the cloned state and\nreturns -ENOMEM, leaving x->mode_data pointing at freed memory.\n\nThe xfrm clone unwind later runs destroy_state() through x->mode_data,\nso the failed clone path tears down IPTFS state that clone_state()\nalready freed.\n\nKeep the cloned IPTFS state private until all allocations succeed so\nfailed clones leave x->mode_data unset. The destroy path already\nhandles a NULL mode_data pointer."}], "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-415"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "6.18.21", "matchCriteriaId": "A92793EC-8117-409C-996C-47A04124C722"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.11", "matchCriteriaId": "4CA2E747-A9EC-4518-9AA2-B4247FC748B7"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/371a43c4ac70cac0de9f9b1fc5b1660b9565b9f1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/5784a1e2889c9525a8f036cb586930e232170bf7", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d849a2f7309fc0616e79d13b008b0a47e0458b6e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}