CVE-2026-74667

Estado: RecibidaAlta (7.8)—

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

net/packet: reset the MAC header on the packet-socket transmit path

packet_parse_headers() resets the MAC header only for a SOCK_RAW frame whose socket did not bind a protocol. A protocol-bound SOCK_RAW socket, any SOCK_DGRAM frame, and the legacy SOCK_PACKET path therefore leave skb->mac_header unset here.

For frames sent via __dev_queue_xmit() this is harmless: it resets the MAC header unconditionally.

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But the packet-socket PACKET_QDISC_BYPASS path uses dev_direct_xmit(), which does not, so the frame reaches ndo_start_xmit() with the MAC header unset. A driver that reads eth_hdr(skb) on transmit then dereferences skb->head + (u16)~0, an out-of-bounds access ~64 KiB past the head -- the same class fixed for one consumer in commit f5089008f90c ("macsec: do not read an unset MAC header in macsec_encrypt()").

packet_parse_headers() runs only on the transmit path, where skb->data points at the start of the L2 header for every packet-socket type regardless of its length: SOCK_RAW and SOCK_PACKET carry a user-supplied header and SOCK_DGRAM has one built by dev_hard_header(). Reset the MAC header unconditionally, mirroring __dev_queue_xmit(), so the frame is anchored on the bypass path too.

Found by 0sec (https://0sec.ai) using automated source analysis; verified against source and matched to the macsec KASAN report in f5089008f90c. Compile-tested.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.14%
Percentil entre todas las CVEs puntuadas: 3
Fecha de la puntuación: 5/10/2026

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.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1499.004 Application or System Exploitationimpact75 %
Impacto secundarioT1005 Data from Local Systemcollection60 %

Vulnerabilidad local (AV:L/PR:L) que permite acceso fuera de límites (~64 KiB) en memoria del kernel via packet-socket bypass, escalando privilegios o causando DoS. Requiere privilegio local para enviar tramas. Lectura de datos de memoria como impacto secundario potencial.

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

Threat Intelligence Program Filter Network Traffic Execution Prevention Application Isolation and Sandboxing Exploit Protection Update Software

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)

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{
  "id": "CVE-2026-74667",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      }
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  "affected": [
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      "affectedData": [
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          "vendor": "Linux",
          "product": "Linux",
          "versions": [
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              "lessThan": "1e43a1d66615f411d427f9df1f46dd049d9e3681",
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          "programFiles": [
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              "version": "5.15.216",
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            },
            {
              "status": "unaffected",
              "version": "6.1.183",
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            },
            {
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              "version": "6.6.152",
              "versionType": "semver",
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            },
            {
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              "version": "6.12.104",
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              "lessThanOrEqual": "6.12.*"
            },
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              "version": "7.1.9",
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            }
          ],
          "programFiles": [
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          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-22T16:16:40.580",
  "references": [
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      "url": "https://git.kernel.org/stable/c/1e43a1d66615f411d427f9df1f46dd049d9e3681",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/packet: reset the MAC header on the packet-socket transmit path\n\npacket_parse_headers() resets the MAC header only for a SOCK_RAW frame\nwhose socket did not bind a protocol. A protocol-bound SOCK_RAW socket,\nany SOCK_DGRAM frame, and the legacy SOCK_PACKET path therefore leave\nskb->mac_header unset here.\n\nFor frames sent via __dev_queue_xmit() this is harmless: it resets the\nMAC header unconditionally. But the packet-socket PACKET_QDISC_BYPASS\npath uses dev_direct_xmit(), which does not, so the frame reaches\nndo_start_xmit() with the MAC header unset. A driver that reads\neth_hdr(skb) on transmit then dereferences skb->head + (u16)~0, an\nout-of-bounds access ~64 KiB past the head -- the same class fixed for\none consumer in commit f5089008f90c (\"macsec: do not read an unset MAC\nheader in macsec_encrypt()\").\n\npacket_parse_headers() runs only on the transmit path, where skb->data\npoints at the start of the L2 header for every packet-socket type\nregardless of its length: SOCK_RAW and SOCK_PACKET carry a user-supplied\nheader and SOCK_DGRAM has one built by dev_hard_header(). Reset the MAC\nheader unconditionally, mirroring __dev_queue_xmit(), so the frame is\nanchored on the bypass path too.\n\nFound by 0sec (https://0sec.ai) using automated source analysis;\nverified against source and matched to the macsec KASAN report in\nf5089008f90c. Compile-tested."
    }
  ],
  "lastModified": "2026-08-25T06:18:48.573",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}