CVE-2026-93203

Estado: RecibidaAlta (7.1)—

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

batman-adv: bla: avoid CRC corruption due to parallel claim add

batadv_bla_add_claim() is used to add claims and modify the backbone of claims for CLAIM frames from remote backbones and local packets. When it handles a claim, it needs to either

* add the new claim's CRC to the backbone CRC * remove the already existing claim's CRC from the old backbone and add it to the new backbone

But when the "new" claim code was running in parallel to the "change backbone" code, it can happen that the CRC was invalid because the backbone_gw of the claim was changed twice in the "new" claim code path:

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The CRC is then wrong for both:

* claim belongs to A: but CRC is not part of backbone A's CRC * claim doesn't belong to B: CRC is still part of backbone B's CRC

This wrong CRC is never recomputated from the stored claims. For local backbone claims, this can also not recovered using syncs.

To avoid this, split the functionality in clear separate parts:

Detalles técnicos trazas, registros y código del informe original

* CPU0 creates the claim for gateway A and publishes it in the claim
  hash. The crc16 of the address has not yet been added to A's crc at
  this point.

* CPU1 processes a claim frame of gateway B for the same client, finds
  the just published claim, and performs the ownership change: it
  switches the pointer to B, removes the crc16 from A's crc - which
  never contained it - and adds it to B's crc.

* CPU0 continues behind the creation branch, unconditionally switches
  the pointer back to A without compensating B's crc (its remove_crc
  is false for the creation path), and finally adds the crc16 to A's
  crc

* new claim which always adds claim CRC to the backbone CRC (but never
  changes the already set backbone_gw of the claim back)

* update of existing claim which automatically changes the backbone_gw
  entry and only updates both backbone CRCs when there was an actual change

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Puntuación base: 7.1

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.41%
Percentil entre todas las CVEs puntuadas: 33
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.

ExplotaciónT1210 Exploitation of Remote Serviceslateral movement60 %

Inferido por reglas deterministas a partir del vector CVSS y la CWE. Solo orientativo.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Vulnerability Scanning Threat Intelligence Program Privileged Account Management Network Segmentation Disable or Remove Feature or Program 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-2026-93203",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.1,
          "attackVector": "ADJACENT_NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
          "integrityImpact": "LOW",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
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        "impactScore": 4.2,
        "exploitabilityScore": 2.8
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      "affectedData": [
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  "published": "2026-09-17T17:18:16.627",
  "references": [
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      "url": "https://git.kernel.org/stable/c/08645ab95768b88e2ff85a89211994651710465b",
      "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\nbatman-adv: bla: avoid CRC corruption due to parallel claim add\n\nbatadv_bla_add_claim() is used to add claims and modify the backbone of\nclaims for CLAIM frames from remote backbones and local packets. When it\nhandles a claim, it needs to either\n\n* add the new claim's CRC to the backbone CRC\n* remove the already existing claim's CRC from the old backbone and add it\n  to the new backbone\n\nBut when the \"new\" claim code was running in parallel to the \"change\nbackbone\" code, it can happen that the CRC was invalid because the\nbackbone_gw of the claim was changed twice in the \"new\" claim code path:\n\n* CPU0 creates the claim for gateway A and publishes it in the claim\n  hash. The crc16 of the address has not yet been added to A's crc at\n  this point.\n\n* CPU1 processes a claim frame of gateway B for the same client, finds\n  the just published claim, and performs the ownership change: it\n  switches the pointer to B, removes the crc16 from A's crc - which\n  never contained it - and adds it to B's crc.\n\n* CPU0 continues behind the creation branch, unconditionally switches\n  the pointer back to A without compensating B's crc (its remove_crc\n  is false for the creation path), and finally adds the crc16 to A's\n  crc\n\nThe CRC is then wrong for both:\n\n* claim belongs to A: but CRC is not part of backbone A's CRC\n* claim doesn't belong to B: CRC is still part of backbone B's CRC\n\nThis wrong CRC is never recomputated from the stored claims. For local\nbackbone claims, this can also not recovered using syncs.\n\nTo avoid this, split the functionality in clear separate parts:\n\n* new claim which always adds claim CRC to the backbone CRC (but never\n  changes the already set backbone_gw of the claim back)\n\n* update of existing claim which automatically changes the backbone_gw\n  entry and only updates both backbone CRCs when there was an actual change"
    }
  ],
  "lastModified": "2026-09-18T18:18:25.057",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}