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CVE-2026-74478

Estado: RecibidaCrítica (9.8)—

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

um: vector: fix use-after-free in vector_mmsg_rx()

When vector_mmsg_rx() discards a packet whose overlay header fails verify_header(), it frees the skb and continues the loop:

The normal and short-packet paths fall through to the bottom of the loop body, which clears the consumed slot and advances the cursors:

The verify_header() < 0 path skips that via continue, so the freed skb is left in skbuff_vector[] and the cursors do not advance. The next iteration reads the same slot, gets the freed skb, and frees it again, producing a refcount underflow / use-after-free in the RX path.

Leer descripción completaMostrar menos

Discard the slot the same way the other paths do before continuing.

Only transports whose verify_header() can return negative are affected: GRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not), so any peer on such a transport can trigger it without authentication.

Detalles técnicos trazas, registros y código del informe original
	if (header_check < 0) {
		dev_kfree_skb_irq(skb);
		vp->estats.rx_encaps_errors++;
		continue;
	}

	(*skbuff_vector) = NULL;
	mmsg_vector++;
	skbuff_vector++;

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).

🎯 Técnicas ATT&CK

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

Red sin autenticación (AV:N, PR:N, UI:N) sobre Linux kernel. Use-after-free con refcount underflow permite DoS (A:H) y potencial escalada local (I:H). GRE/L2TPv3 explotables sin auth.

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 TrafficVulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkApplication 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 KernelAI

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-74478",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "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": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb",
              "lessThan": "967c779c9853d2a1cc9cd8e61d300250c348f3d9",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb",
              "lessThan": "a7bc015bb798c525e7a82dd14225c6aeb994274b",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb",
              "lessThan": "7dc9781e320d664c9bdd50003c9acfddf363d1e1",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb",
              "lessThan": "4b9601595e8b6b5d18878cac0aeabc687d241111",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb",
              "lessThan": "67d58ab4f2ccf7145f3da07e025735a09c79de1b",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb",
              "lessThan": "180ff4c81faf01ec4e06082c9daa7c40518ead89",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb",
              "lessThan": "804b681002ead233abf49a3efd681f5468a835f9",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb",
              "lessThan": "af421e9aed3920c7ac88c24daa48606c7112feca",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "arch/um/drivers/vector_kern.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.17"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "4.17",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.10.265",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "status": "unaffected",
              "version": "5.15.216",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.1.183",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.151",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.103",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.44",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "arch/um/drivers/vector_kern.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-15T13:17:52.600",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/180ff4c81faf01ec4e06082c9daa7c40518ead89",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/4b9601595e8b6b5d18878cac0aeabc687d241111",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/67d58ab4f2ccf7145f3da07e025735a09c79de1b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/7dc9781e320d664c9bdd50003c9acfddf363d1e1",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/804b681002ead233abf49a3efd681f5468a835f9",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/967c779c9853d2a1cc9cd8e61d300250c348f3d9",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a7bc015bb798c525e7a82dd14225c6aeb994274b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/af421e9aed3920c7ac88c24daa48606c7112feca",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\num: vector: fix use-after-free in vector_mmsg_rx()\n\nWhen vector_mmsg_rx() discards a packet whose overlay header fails\nverify_header(), it frees the skb and continues the loop:\n\n\tif (header_check < 0) {\n\t\tdev_kfree_skb_irq(skb);\n\t\tvp->estats.rx_encaps_errors++;\n\t\tcontinue;\n\t}\n\nThe normal and short-packet paths fall through to the bottom of the\nloop body, which clears the consumed slot and advances the cursors:\n\n\t(*skbuff_vector) = NULL;\n\tmmsg_vector++;\n\tskbuff_vector++;\n\nThe verify_header() < 0 path skips that via continue, so the freed skb\nis left in skbuff_vector[] and the cursors do not advance. The next\niteration reads the same slot, gets the freed skb, and frees it again,\nproducing a refcount underflow / use-after-free in the RX path.\n\nDiscard the slot the same way the other paths do before continuing.\n\nOnly transports whose verify_header() can return negative are affected:\nGRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not),\nso any peer on such a transport can trigger it without authentication."
    }
  ],
  "lastModified": "2026-08-19T17:21:04.947",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}