CVE-2026-97906 (GCVE-0-2026-97906)
Vulnerability from cvelistv5
Published
2026-09-25 10:22
Modified
2026-10-21 12:53
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bootconfig: Fix integer overflow in initrd size check Sashiko reported that in get_boot_config_from_initrd(), a crafted initrd with a huge bootconfig size (such as 0xFFFFFFFF) can cause the pointer arithmetic: data = ((void *)hdr) - size; to wrap around on 32-bit systems (or when pointer subtraction overflows). Because data wraps around, the subsequent bounds check: if ((unsigned long)data < initrd_start) evaluates to false, bypassing the check. The kernel then calls xbc_calc_checksum(data, size), which attempts to read 4GB of memory, hitting unmapped pages and triggering a fatal kernel page fault during early boot. Furthermore, on 64-bit systems with an initrd > 4.29 GB, an unbounded 32-bit size can similarly bypass the initrd_start check. Fix this by: 1. Ensuring the initrd is at least large enough to contain the bootconfig footer and verifying hdr is within the initrd bounds. 2. Checking that size does not exceed XBC_DATA_MAX and does not exceed the available space between initrd_start and hdr before performing pointer subtraction.
References
Impacted products
Vendor Product Version
Linux Linux Version: de462e5f10718517bacf2f84c8aa2804567ef7df
Version: de462e5f10718517bacf2f84c8aa2804567ef7df
Version: de462e5f10718517bacf2f84c8aa2804567ef7df
Version: de462e5f10718517bacf2f84c8aa2804567ef7df
Version: de462e5f10718517bacf2f84c8aa2804567ef7df
Version: 32394df25d8e46935b442b429d74b37885c4f092
Version: 5.6.14   ≤
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbootconfig: Fix integer overflow in initrd size check\n\nSashiko reported that in get_boot_config_from_initrd(), a crafted initrd\nwith a huge bootconfig size (such as 0xFFFFFFFF) can cause the pointer\narithmetic:\n\n    data = ((void *)hdr) - size;\n\nto wrap around on 32-bit systems (or when pointer subtraction overflows).\nBecause data wraps around, the subsequent bounds check:\n\n    if ((unsigned long)data \u003c initrd_start)\n\nevaluates to false, bypassing the check. The kernel then calls\nxbc_calc_checksum(data, size), which attempts to read 4GB of memory,\nhitting unmapped pages and triggering a fatal kernel page fault during\nearly boot. Furthermore, on 64-bit systems with an initrd \u003e 4.29 GB, an\nunbounded 32-bit size can similarly bypass the initrd_start check.\n\nFix this by:\n1. Ensuring the initrd is at least large enough to contain the bootconfig\n   footer and verifying hdr is within the initrd bounds.\n2. Checking that size does not exceed XBC_DATA_MAX and does not exceed\n   the available space between initrd_start and hdr before performing\n   pointer subtraction."
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      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:53:32.335Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/97be05f33f79342ea65d9b99c9ad07a93b8eef5a"
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          "url": "https://git.kernel.org/stable/c/4d45bc0f8cdf606d5409b5f64a8a6609f6520c03"
        },
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          "url": "https://git.kernel.org/stable/c/8d4343a411eaa182d323ab5b149496416015f27d"
        },
        {
          "url": "https://git.kernel.org/stable/c/bff9a1579e2c9b2a59fdf3793becc9d7bf5ff1a6"
        },
        {
          "url": "https://git.kernel.org/stable/c/7812d6dab0698001e50e8c2f901e17da3eb6f429"
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      ],
      "title": "bootconfig: Fix integer overflow in initrd size check",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97906",
    "datePublished": "2026-09-25T10:22:31.640Z",
    "dateReserved": "2026-09-25T10:18:58.200Z",
    "dateUpdated": "2026-10-21T12:53:32.335Z",
    "state": "PUBLISHED"
  },
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}


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