CVE-2026-74430

Estado: RecibidaAlta (7.5)—

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

rxrpc: Fix ACKALL packet handling

rxrpc_input_ackall() accepts ACKALL packets without checking whether the call is in a state that can legitimately have outstanding transmit buffers. A forged ACKALL can therefore reach a new service call in RXRPC_CALL_SERVER_RECV_REQUEST before any reply packets have been queued.

In that state call->tx_top is zero and call->tx_queue is NULL, so rxrpc_rotate_tx_window() dereferences a NULL txqueue and triggers a null-pointer dereference.

Fix the handling of ACKALL packets by the following means:

Thanks to Jeffrey Altman for a description of the history of the ACKALL packet[1].

Detalles técnicos trazas, registros y código del informe original

 (1) Add two new call states: RXRPC_CALL_CLIENT_PRE_SEND which indicates
     that the client call is connected, but nothing has been transmitted as
     yet; and RXRPC_CALL_CLIENT_AWAIT_ACK, which indicates that everything
     has been transmitted at least once, but we're now waiting for the
     stuff remaining in the Tx buffer to be ACK'd (retransmissions may
     still happen).

     The RXRPC_CALL_CLIENT_PRE_SEND state is set when the call is assigned
     a channel and transitions to RXRPC_CALL_CLIENT_SEND_REQUEST when the
     first packet is transmitted.

     RXRPC_CALL_CLIENT_AWAIT_REPLY is then narrowed in scope to indicate
     that all Tx packets have been ACK'd and we're now waiting for the
     reply to be received.

 (2) As per Wyatt Feng's original patch[1], the ACKALL handler then checks
     that the call state is one in which there might be stuff in the Tx
     buffer to ACK, but now this includes AWAIT_ACK rather than
     AWAIT_REPLY.  ACKALL packets are ignored if received in the wrong
     state.

     Note that unlike Wyatt Feng's patch, it's no longer necessary to check
     to see if the Tx buffer exists as this the state set now covers this.

 (3) Make the ACKALL handler use call->tx_transmitted rather than
     call->tx_top as the former is explicitly the highest packet seq number
     transmitted, whereas the latter has a looser definition.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Puntuación base: 7.5

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.61%
Percentil entre todas las CVEs puntuadas: 47
Fecha de la puntuación: 6/10/2026

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).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access75 %
Impacto principalT1499.004 Application or System Exploitationimpact80 %

Red sin privilegios (AV:N/PR:N) permite enviar paquete ACKALL forjado causando null-pointer dereference (DoS de aplicación en kernel Linux).

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2026-74430",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "b341a0263b1b804d329f864c2dc24815364510ec",
              "lessThan": "8db6a2c95e36938076b37466ce36774526a5c8c3",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b341a0263b1b804d329f864c2dc24815364510ec",
              "lessThan": "523cb585672ae681b2d3b0d620aec5313774e2e2",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b341a0263b1b804d329f864c2dc24815364510ec",
              "lessThan": "9b6ce594808580b2a19e6e1aa459ef56c0153ac1",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "net/rxrpc/ar-internal.h",
            "net/rxrpc/call_event.c",
            "net/rxrpc/call_object.c",
            "net/rxrpc/conn_client.c",
            "net/rxrpc/input.c",
            "net/rxrpc/sendmsg.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.14",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/rxrpc/ar-internal.h",
            "net/rxrpc/call_event.c",
            "net/rxrpc/call_object.c",
            "net/rxrpc/conn_client.c",
            "net/rxrpc/input.c",
            "net/rxrpc/sendmsg.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-15T06:22:45.120",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/523cb585672ae681b2d3b0d620aec5313774e2e2",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/8db6a2c95e36938076b37466ce36774526a5c8c3",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9b6ce594808580b2a19e6e1aa459ef56c0153ac1",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Fix ACKALL packet handling\n\nrxrpc_input_ackall() accepts ACKALL packets without checking whether the\ncall is in a state that can legitimately have outstanding transmit buffers.\nA forged ACKALL can therefore reach a new service call in\nRXRPC_CALL_SERVER_RECV_REQUEST before any reply packets have been queued.\n\nIn that state call->tx_top is zero and call->tx_queue is NULL, so\nrxrpc_rotate_tx_window() dereferences a NULL txqueue and triggers a\nnull-pointer dereference.\n\nFix the handling of ACKALL packets by the following means:\n\n (1) Add two new call states: RXRPC_CALL_CLIENT_PRE_SEND which indicates\n     that the client call is connected, but nothing has been transmitted as\n     yet; and RXRPC_CALL_CLIENT_AWAIT_ACK, which indicates that everything\n     has been transmitted at least once, but we're now waiting for the\n     stuff remaining in the Tx buffer to be ACK'd (retransmissions may\n     still happen).\n\n     The RXRPC_CALL_CLIENT_PRE_SEND state is set when the call is assigned\n     a channel and transitions to RXRPC_CALL_CLIENT_SEND_REQUEST when the\n     first packet is transmitted.\n\n     RXRPC_CALL_CLIENT_AWAIT_REPLY is then narrowed in scope to indicate\n     that all Tx packets have been ACK'd and we're now waiting for the\n     reply to be received.\n\n (2) As per Wyatt Feng's original patch[1], the ACKALL handler then checks\n     that the call state is one in which there might be stuff in the Tx\n     buffer to ACK, but now this includes AWAIT_ACK rather than\n     AWAIT_REPLY.  ACKALL packets are ignored if received in the wrong\n     state.\n\n     Note that unlike Wyatt Feng's patch, it's no longer necessary to check\n     to see if the Tx buffer exists as this the state set now covers this.\n\n (3) Make the ACKALL handler use call->tx_transmitted rather than\n     call->tx_top as the former is explicitly the highest packet seq number\n     transmitted, whereas the latter has a looser definition.\n\nThanks to Jeffrey Altman for a description of the history of the ACKALL\npacket[1]."
    }
  ],
  "lastModified": "2026-08-17T06:19:38.597",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}