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CVE-2026-23331

Estado: AnalizadaMedia (5.5)—

In the Linux kernel, the following vulnerability has been resolved:

udp: Unhash auto-bound connected sk from 4-tuple hash table when disconnected.

Let's say we bind() an UDP socket to the wildcard address with a non-zero port, connect() it to an address, and disconnect it from the address.

bind() sets SOCK_BINDPORT_LOCK on sk->sk_userlocks (but not SOCK_BINDADDR_LOCK), and connect() calls udp_lib_hash4() to put the socket into the 4-tuple hash table.

Then, __udp_disconnect() calls sk->sk_prot->rehash(sk).

It computes a new hash based on the wildcard address and moves the socket to a new slot in the 4-tuple hash table, leaving a garbage in the chain that no packet hits.

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Let's remove such a socket from 4-tuple hash table when disconnected.

Note that udp_sk(sk)->udp_portaddr_hash needs to be udpated after udp_hash4_dec(hslot2) in udp_unhash4().

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

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  "id": "CVE-2026-23331",
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          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
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  "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->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->sk_prot->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)->udp_portaddr_hash necesita ser actualizado después de udp_hash4_dec(hslot2) en udp_unhash4()."
    }
  ],
  "lastModified": "2026-06-17T10:21:20.567",
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