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CVE-2026-80521

Estado: RecibidaAlta (7.8)—

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

af_unix: Unlink scc_entry in unix_del_edge().

Kyle Zeng reported that GC could free a dead SCC partially.

The scenario is as follows:

At 2-1), there is a small window where unix_add_edges() publishes a new edge (B <-> B) to GC but its skb is not queued by skb_queue_tail().

If 2-2) completes before skb_queue_tail() and GC is triggered, it judges A <-> B as dead, but B is not freed because GC cannot collect the not-yet-queued skb holding the B <-> B edge.

This itself is not a problem since the next GC run will judge B as dead as well and free it finally.

Leer descripción completaMostrar menos

However, X's SCC forces the next GC to call unix_walk_scc_fast(), and it iterates over A through B's scc_entry.

Let's unlink scc_entry before freeing the vertex in unix_del_edge().

Detalles técnicos trazas, registros y código del informe original
   1) Create two SCCs:

       X -.   A <-> B
       ^--'

   2) Run the following concurrently:

      2-1) send() sk-B to sk-B from sk-X
      2-2) close() both A and B

       X -.   A <-> B -. This edge is visible
       ^--'         ^..'  but skb is not

       X -.   A <.> B -.
       ^--'         ^--'

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.

Vulnerabilidad de escalada de privilegios en kernel Linux (AV:L, PR:L) que permite DoS por corrupción de memoria en el recolector de basura de unix sockets; el atacante con permisos locales puede provocar uso después de liberación (UAF) y crash del sistema.

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 ProgramFilter Network TrafficExecution PreventionApplication Isolation and SandboxingExploit ProtectionUpdate 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 KernelAI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-80521",
  "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
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
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              "version": "5dfd283f4651d04dbb70ceb9ae5c4a30eda3c52a",
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            {
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          "programFiles": [
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          "defaultStatus": "unaffected"
        },
        {
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          "vendor": "Linux",
          "product": "Linux",
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              "version": "6.10"
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              "version": "0",
              "lessThan": "6.10",
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              "version": "6.1.189",
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            },
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              "version": "6.12.111",
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            },
            {
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            {
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              "version": "7.2",
              "versionType": "original_commit_for_fix",
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            }
          ],
          "programFiles": [
            "net/unix/garbage.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-26T15:17:05.677",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/1293fd69a50d188a5788b08ba3741a3e86be1608",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/2b6c2842692d08e7acaf32d1eb47f95def35f3fe",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/594d905195024b228c962627ae5ae7c17bd582a4",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6fda5c51b8e43a8440f76e65c89d9f95ddb2ef33",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "url": "https://git.kernel.org/stable/c/e3702470ced94fad74d71e2232f022d2eb752a6d",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
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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\naf_unix: Unlink scc_entry in unix_del_edge().\n\nKyle Zeng reported that GC could free a dead SCC partially.\n\nThe scenario is as follows:\n\n   1) Create two SCCs:\n\n       X -.   A <-> B\n       ^--'\n\n   2) Run the following concurrently:\n\n      2-1) send() sk-B to sk-B from sk-X\n      2-2) close() both A and B\n\nAt 2-1), there is a small window where unix_add_edges()\npublishes a new edge (B <-> B) to GC but its skb is not queued\nby skb_queue_tail().\n\nIf 2-2) completes before skb_queue_tail() and GC is triggered,\nit judges A <-> B as dead, but B is not freed because GC cannot\ncollect the not-yet-queued skb holding the B <-> B edge.\n\n       X -.   A <-> B -. This edge is visible\n       ^--'         ^..'  but skb is not\n\nThis itself is not a problem since the next GC run will judge\nB as dead as well and free it finally.\n\n       X -.   A <.> B -.\n       ^--'         ^--'\n\nHowever, X's SCC forces the next GC to call unix_walk_scc_fast(),\nand it iterates over A through B's scc_entry.\n\nLet's unlink scc_entry before freeing the vertex in unix_del_edge()."
    }
  ],
  "lastModified": "2026-10-03T11:17:39.437",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}