Linux Kernel Missing Initialization of a Variable Vulnerability

{
  "id": "5b31af9d5ac3d7c1fbc272de603d6fa7aa36c311ea52b35b9165912c47983ef4",
  "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-46300",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Linux Kernel Missing Initialization of a Variable Vulnerability",
    "summary": "Linux Kernel contains a missing initialization of a variable vulnerability that could allow for unintended modification of page-cache-backed data via failure to preserve the shared-fragment marker during socket buffer coalescing, causing ESP input processing to decrypt shared fragments in place. This vulnerability can be chained with CVE-2026-109618 and CVE-2026-109619 to implant PHP webshells and run commands as root. CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.",
    "evidence": "kev:CVE-2026-46300",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-46300",
      "aliases": [
        "CVE-2026-46300"
      ],
      "affected": [],
      "modified": "2026-10-28T00:00:00.000Z",
      "provider": "kev",
      "references": [
        "https://www.cisa.gov/known-exploited-vulnerabilities-catalog"
      ],
      "exploitation": {
        "cwes": [
          "CWE-456"
        ],
        "cveID": "CVE-2026-46300",
        "notes": "This vulnerability affects an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: ; https://git.kernel.org/stable/c/3599e6b3cc1ada96883d496a50a210d3afbb6987 ; https://git.kernel.org/stable/c/2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c ; https://git.kernel.org/stable/c/9d3e5fd19fe1063bf607219e8562fbd567b8e8d5 ; https://git.kernel.org/stable/c/78bf6b6bb19541d19fbda6242e7cfe2c682763c0 ; https://git.kernel.org/stable/c/760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e ; https://git.kernel.org/stable/c/3bd9e113d50034db99d7ef69fd8e5242d15e414a ; https://git.kernel.org/stable/c/3884358a9286b17f389a72b1426fc4547c23c111 ; https://git.kernel.org/stable/c/f84eca5817390257cef78013d0112481c503b4a3 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-46300",
        "dueDate": "2026-10-31",
        "product": "Kernel",
        "dateAdded": "2026-10-28",
        "vendorProject": "Linux",
        "requiredAction": "Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.",
        "known_exploited": true,
        "shortDescription": "Linux Kernel contains a missing initialization of a variable vulnerability that could allow for unintended modification of page-cache-backed data via failure to preserve the shared-fragment marker during socket buffer coalescing, causing ESP input processing to decrypt shared fragments in place. This vulnerability can be chained with CVE-2026-109618 and CVE-2026-109619 to implant PHP webshells and run commands as root.",
        "vulnerabilityName": "Linux Kernel Missing Initialization of a Variable Vulnerability",
        "knownRansomwareCampaignUse": "Unknown"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-46300",
        "evidence": "/cveID"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-kev",
  "document_id": 501198,
  "published_at": "2026-10-28T00:00:00+00:00"
}