GHSA-GC6W-QCF3-4MHM
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33In the Linux kernel, the following vulnerability has been resolved:
ntfs3: bound to_move in indx_insert_into_root before hdr_insert_head
indx_insert_into_root() promotes a full resident $INDEX_ROOT into $INDEX_ALLOCATION and copies all non-last resident root entries into a newly allocated INDEX_BUFFER via hdr_insert_head(). The source byte count 'to_move' is summed from the on-disk resident entry sizes and is independent of the destination buffer size, which comes from root->index_block_size (via indx->index_bits).
A crafted NTFS image that keeps a valid, full resident root but shrinks root->index_block_size down to 512 after the root has been populated makes hdr_insert_head() memcpy attacker-controlled resident entry bytes past the end of the kmalloc(1u << indx->index_bits) allocation returned by indx_new(). For a 512-byte destination and a resident root whose non-last entries total 560 bytes, the memcpy overruns by 120 bytes and a following memmove extends the highest written offset to 136 bytes past the allocation. The overflow bytes are a direct copy of on-disk entries (via kmemdup), so they are fully attacker-controlled.
The write is reachable from unprivileged open(O_CREAT) on a mounted crafted NTFS image: a single sufficiently long create in a directory whose resident root is already full forces root promotion and triggers the copy.
This is a controlled out-of-bounds write of 120-136 bytes past a kmalloc(index_block_size) allocation, with attacker-controlled content. It is a bounded adjacent-heap corruption primitive; it is not an arbitrary-address write. Successful exploitation into a named victim object depends on the surrounding slab layout.
Reject the copy at the sink. The destination's INDEX_HDR already reports hdr_total (the payload capacity of the new buffer) and hdr_used (the bytes already consumed by the terminal END entry installed by indx_new()); require that to_move fits in the remaining payload before calling hdr_insert_head(). On mismatch, fail with -EINVAL and mark the filesystem as having a detected on-disk inconsistency, which is the same behaviour as the surrounding validation in this function.
{
"affected": [],
"aliases": [
"CVE-2026-72192"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:21:37Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nntfs3: bound to_move in indx_insert_into_root before hdr_insert_head\n\nindx_insert_into_root() promotes a full resident $INDEX_ROOT into\n$INDEX_ALLOCATION and copies all non-last resident root entries into\na newly allocated INDEX_BUFFER via hdr_insert_head(). The source\nbyte count \u0027to_move\u0027 is summed from the on-disk resident entry sizes\nand is independent of the destination buffer size, which comes from\nroot-\u003eindex_block_size (via indx-\u003eindex_bits).\n\nA crafted NTFS image that keeps a valid, full resident root but\nshrinks root-\u003eindex_block_size down to 512 after the root has been\npopulated makes hdr_insert_head() memcpy attacker-controlled resident\nentry bytes past the end of the kmalloc(1u \u003c\u003c indx-\u003eindex_bits)\nallocation returned by indx_new(). For a 512-byte destination and a\nresident root whose non-last entries total 560 bytes, the memcpy\noverruns by 120 bytes and a following memmove extends the highest\nwritten offset to 136 bytes past the allocation. The overflow bytes\nare a direct copy of on-disk entries (via kmemdup), so they are\nfully attacker-controlled.\n\nThe write is reachable from unprivileged open(O_CREAT) on a mounted\ncrafted NTFS image: a single sufficiently long create in a directory\nwhose resident root is already full forces root promotion and\ntriggers the copy.\n\nThis is a controlled out-of-bounds write of 120-136 bytes past a\nkmalloc(index_block_size) allocation, with attacker-controlled\ncontent. It is a bounded adjacent-heap corruption primitive; it is\nnot an arbitrary-address write. Successful exploitation into a named\nvictim object depends on the surrounding slab layout.\n\nReject the copy at the sink. The destination\u0027s INDEX_HDR already\nreports hdr_total (the payload capacity of the new buffer) and\nhdr_used (the bytes already consumed by the terminal END entry\ninstalled by indx_new()); require that to_move fits in the remaining\npayload before calling hdr_insert_head(). On mismatch, fail with\n-EINVAL and mark the filesystem as having a detected on-disk\ninconsistency, which is the same behaviour as the surrounding\nvalidation in this function.",
"id": "GHSA-gc6w-qcf3-4mhm",
"modified": "2026-08-17T06:33:15Z",
"published": "2026-08-15T06:32:15Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72192"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0af83b8155cc848e9f5d2c36e20a70d024214649"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/194b00c99ba971fa7cf6acd747a36032c6de54eb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/53c5f3b2da3774b41534728aba295c098c9efa19"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9b6926ac9c970ae0b2c2fe6289b16e9aa10b6a67"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/aaa1f956c0fc41089a4a534da7df91552a08a47c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cb3161deebcaf8d36d3115abf452c633f2180fc1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d240f5f9d036b8180224954d9873f172b6be4dd8"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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