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CVE-2026-80631

Estado: RecibidaAlta (7.5)—

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

btrfs: lzo: reject compressed segment that overflows the compressed input

lzo_decompress_bio() validates each on-disk segment length seg_len only against the workspace cbuf size, not against the compressed input size (compressed_len, the total folio bytes of the bio). A crafted extent can carry a segment whose seg_len passes the cbuf check but runs past the end of the bio, so copy_compressed_segment() walks off the last folio: get_current_folio() then returns the NULL folio from bio_next_folio(), and with CONFIG_BTRFS_ASSERT disabled (default) folio_size(NULL) faults.

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Reject any segment whose payload would extend beyond compressed_len before copying it, treating it as corruption like the other on-disk validation failures in this function.

Detalles técnicos trazas, registros y código del informe original
 BUG: KASAN: null-ptr-deref in lzo_decompress_bio (fs/btrfs/lzo.c:383)
 Read of size 8 at addr 0000000000000000 by task kworker/u8:1/29
 Workqueue: btrfs-endio simple_end_io_work
  kasan_report (mm/kasan/report.c:590)
  lzo_decompress_bio (fs/btrfs/lzo.c:383)
  end_bbio_compressed_read (fs/btrfs/compression.c:1065)
  btrfs_bio_end_io (fs/btrfs/bio.c:135)
  btrfs_check_read_bio (fs/btrfs/bio.c:180 fs/btrfs/bio.c:285)
  simple_end_io_work
  process_one_work
  worker_thread

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.

Vector AV:N/PR:N/UI:N indica explotación remota sin privilegios (T1190). La vulnerabilidad en descompresión LZO causa null-ptr-deref que provoca DoS del kernel (A:H en CVSS), específicamente denegación de servicio por crash de la aplicación (T1499.004).

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)

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{
  "id": "CVE-2026-80631",
  "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": "a6e66e6f8c1b685e11b778bef614480a9c1a5278",
              "lessThan": "1641d058adfbd50cf95d54581ed5d142ee82c07f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "a6e66e6f8c1b685e11b778bef614480a9c1a5278",
              "lessThan": "b0d27d43791b7a3057c3c4aedf9b4aa033d37c46",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/btrfs/lzo.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "5.15",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/btrfs/lzo.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-28T08:16:48.010",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/1641d058adfbd50cf95d54581ed5d142ee82c07f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b0d27d43791b7a3057c3c4aedf9b4aa033d37c46",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: lzo: reject compressed segment that overflows the compressed input\n\nlzo_decompress_bio() validates each on-disk segment length seg_len only\nagainst the workspace cbuf size, not against the compressed input size\n(compressed_len, the total folio bytes of the bio).  A crafted extent can\ncarry a segment whose seg_len passes the cbuf check but runs past the end\nof the bio, so copy_compressed_segment() walks off the last folio:\nget_current_folio() then returns the NULL folio from bio_next_folio(), and\nwith CONFIG_BTRFS_ASSERT disabled (default) folio_size(NULL) faults.\n\n BUG: KASAN: null-ptr-deref in lzo_decompress_bio (fs/btrfs/lzo.c:383)\n Read of size 8 at addr 0000000000000000 by task kworker/u8:1/29\n Workqueue: btrfs-endio simple_end_io_work\n  kasan_report (mm/kasan/report.c:590)\n  lzo_decompress_bio (fs/btrfs/lzo.c:383)\n  end_bbio_compressed_read (fs/btrfs/compression.c:1065)\n  btrfs_bio_end_io (fs/btrfs/bio.c:135)\n  btrfs_check_read_bio (fs/btrfs/bio.c:180 fs/btrfs/bio.c:285)\n  simple_end_io_work\n  process_one_work\n  worker_thread\n\nReject any segment whose payload would extend beyond compressed_len before\ncopying it, treating it as corruption like the other on-disk validation\nfailures in this function."
    }
  ],
  "lastModified": "2026-08-29T07:16:47.210",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}