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CVE-2025-21854

Estado: ModificadaMedia (5.5)—

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

sockmap, vsock: For connectible sockets allow only connected

sockmap expects all vsocks to have a transport assigned, which is expressed in vsock_proto::psock_update_sk_prot(). However, there is an edge case where an unconnected (connectible) socket may lose its previously assigned transport. This is handled with a NULL check in the vsock/BPF recv path.

Another design detail is that listening vsocks are not supposed to have any transport assigned at all. Which implies they are not supported by the sockmap.

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But this is complicated by the fact that a socket, before switching to TCP_LISTEN, may have had some transport assigned during a failed connect() attempt. Hence, we may end up with a listening vsock in a sockmap, which blows up quickly:

For connectible sockets, instead of relying solely on the state of vsk->transport, tell sockmap to only allow those representing established connections. This aligns with the behaviour for AF_INET and AF_UNIX.

Detalles técnicos trazas, registros y código del informe original
KASAN: null-ptr-deref in range [0x0000000000000120-0x0000000000000127]
CPU: 7 UID: 0 PID: 56 Comm: kworker/7:0 Not tainted 6.14.0-rc1+
Workqueue: vsock-loopback vsock_loopback_work
RIP: 0010:vsock_read_skb+0x4b/0x90
Call Trace:
 sk_psock_verdict_data_ready+0xa4/0x2e0
 virtio_transport_recv_pkt+0x1ca8/0x2acc
 vsock_loopback_work+0x27d/0x3f0
 process_one_work+0x846/0x1420
 worker_thread+0x5b3/0xf80
 kthread+0x35a/0x700
 ret_from_fork+0x2d/0x70
 ret_from_fork_asm+0x1a/0x30

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)

Mostrar
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  "id": "CVE-2025-21854",
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      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsockmap, vsock: For connectible sockets allow only connected\n\nsockmap expects all vsocks to have a transport assigned, which is expressed\nin vsock_proto::psock_update_sk_prot(). However, there is an edge case\nwhere an unconnected (connectible) socket may lose its previously assigned\ntransport. This is handled with a NULL check in the vsock/BPF recv path.\n\nAnother design detail is that listening vsocks are not supposed to have any\ntransport assigned at all. Which implies they are not supported by the\nsockmap. But this is complicated by the fact that a socket, before\nswitching to TCP_LISTEN, may have had some transport assigned during a\nfailed connect() attempt. Hence, we may end up with a listening vsock in a\nsockmap, which blows up quickly:\n\nKASAN: null-ptr-deref in range [0x0000000000000120-0x0000000000000127]\nCPU: 7 UID: 0 PID: 56 Comm: kworker/7:0 Not tainted 6.14.0-rc1+\nWorkqueue: vsock-loopback vsock_loopback_work\nRIP: 0010:vsock_read_skb+0x4b/0x90\nCall Trace:\n sk_psock_verdict_data_ready+0xa4/0x2e0\n virtio_transport_recv_pkt+0x1ca8/0x2acc\n vsock_loopback_work+0x27d/0x3f0\n process_one_work+0x846/0x1420\n worker_thread+0x5b3/0xf80\n kthread+0x35a/0x700\n ret_from_fork+0x2d/0x70\n ret_from_fork_asm+0x1a/0x30\n\nFor connectible sockets, instead of relying solely on the state of\nvsk->transport, tell sockmap to only allow those representing established\nconnections. This aligns with the behaviour for AF_INET and AF_UNIX."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: sockmap, vsock: Para sockets conectables, solo se permite que estén conectados. Sockmap espera que todos los vsocks tengan un transporte asignado, lo cual se expresa en vsock_proto::psock_update_sk_prot(). Sin embargo, existe un caso extremo en el que un socket no conectado (conectable) puede perder su transporte previamente asignado. Esto se gestiona con una comprobación de NULL en la ruta de recepción vsock/BPF. Otro detalle de diseño es que los vsocks que escuchan no deben tener ningún transporte asignado. Esto implica que no son compatibles con sockmap. Sin embargo, esto se complica por el hecho de que un socket, antes de cambiar a TCP_LISTEN, puede haber tenido algún transporte asignado durante un intento fallido de connect(). Por lo tanto, podemos terminar con un vsock escuchando en un sockmap, que explota rápidamente: KASAN: null-ptr-deref en el rango [0x0000000000000120-0x0000000000000127] CPU: 7 UID: 0 PID: 56 Comm: kworker/7:0 No contaminado 6.14.0-rc1+ Cola de trabajo: vsock-loopback vsock_loopback_work RIP: 0010:vsock_read_skb+0x4b/0x90 Rastreo de llamadas: sk_psock_verdict_data_ready+0xa4/0x2e0 virtio_transport_recv_pkt+0x1ca8/0x2acc vsock_loopback_work+0x27d/0x3f0 Para los sockets conectables, en lugar de depender únicamente del estado de vsk->transport, indique a sockmap que solo permita los que representan conexiones establecidas. Esto coincide con el comportamiento de AF_INET y AF_UNIX."
    }
  ],
  "lastModified": "2026-06-17T08:44:27.060",
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