CVE-2026-97415 (GCVE-0-2026-97415)
Vulnerability from cvelistv5 – Published: 2026-09-24 16:03 – Updated: 2026-10-03 10:58
VLAI
EPSS
VEX
Title
btrfs: tree-checker: validate names in ROOT_REF and ROOT_BACKREF
Summary
In the Linux kernel, the following vulnerability has been resolved:
btrfs: tree-checker: validate names in ROOT_REF and ROOT_BACKREF
ROOT_REF and ROOT_BACKREF items contain a struct btrfs_root_ref followed
by the subvolume name. Several readers assume that this layout is already
valid and then use the on-disk name length directly. A corrupted item can
therefore make those readers address bytes outside the item, and
BTRFS_IOC_GET_SUBVOL_INFO can copy too many bytes into its fixed-size UAPI
name buffer.
Validate ROOT_REF and ROOT_BACKREF items in tree-checker before any reader
uses them. Reject records that do not contain a non-empty name, whose
name_len does not exactly describe the remaining item payload, or whose
name exceeds BTRFS_NAME_LEN.
For BTRFS_IOC_GET_SUBVOL_INFO, copy only the validated on-disk name_len
instead of deriving the copy length from the item size. The ioctl result is
zeroed when allocated. That leaves the existing trailing zero byte
untouched.
Severity
7.8 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
b64ec075bded2b30bcd90af5aa5256d2237c885d , < 1370badf6b823ce3cde39a65f46f9e5dc7b4bf43
(git)
Affected: b64ec075bded2b30bcd90af5aa5256d2237c885d , < ba6c4fc662853f6662e4db060cf88ee994053e21 (git) Affected: b64ec075bded2b30bcd90af5aa5256d2237c885d , < 9154542070ca7eadb3c764a882f39a127677854b (git) Affected: b64ec075bded2b30bcd90af5aa5256d2237c885d , < 74f577c722c99248d804eca18e7de7c5e47549d7 (git) Affected: b64ec075bded2b30bcd90af5aa5256d2237c885d , < 0af37c217edf15fa21dac1c40822086df356c6bb (git) |
guessed | |
| Linux | Linux |
Affected:
4.18
Unaffected: 0 , < 4.18 (semver) Unaffected: 6.1.189 , ≤ 6.1.* (semver) Unaffected: 6.6.158 , ≤ 6.6.* (semver) Unaffected: 6.12.111 , ≤ 6.12.* (semver) Unaffected: 6.18.53 , ≤ 6.18.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
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"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/btrfs/ioctl.c",
"fs/btrfs/tree-checker.c"
],
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"vendor": "Linux",
"versions": [
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"versionType": "git"
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{
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"programFiles": [
"fs/btrfs/ioctl.c",
"fs/btrfs/tree-checker.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.18"
},
{
"lessThan": "4.18",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.1.189",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.111",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.53",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.189",
"versionStartIncluding": "4.18",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.158",
"versionStartIncluding": "4.18",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.111",
"versionStartIncluding": "4.18",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.53",
"versionStartIncluding": "4.18",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "4.18",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: tree-checker: validate names in ROOT_REF and ROOT_BACKREF\n\nROOT_REF and ROOT_BACKREF items contain a struct btrfs_root_ref followed\nby the subvolume name. Several readers assume that this layout is already\nvalid and then use the on-disk name length directly. A corrupted item can\ntherefore make those readers address bytes outside the item, and\nBTRFS_IOC_GET_SUBVOL_INFO can copy too many bytes into its fixed-size UAPI\nname buffer.\n\nValidate ROOT_REF and ROOT_BACKREF items in tree-checker before any reader\nuses them. Reject records that do not contain a non-empty name, whose\nname_len does not exactly describe the remaining item payload, or whose\nname exceeds BTRFS_NAME_LEN.\n\nFor BTRFS_IOC_GET_SUBVOL_INFO, copy only the validated on-disk name_len\ninstead of deriving the copy length from the item size. The ioctl result is\nzeroed when allocated. That leaves the existing trailing zero byte\nuntouched."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The attacker-controlled bytes are the on-disk BTRFS_ROOT_BACKREF_KEY item (struct btrfs_root_ref plus the following name) in the tree of tree roots. After that image is mounted, ioctl(BTRFS_IOC_GET_SUBVOL_INFO) reaches _btrfs_ioctl_get_subvol_info() via btrfs_ioctl() and read_extent_buffer()s the item; no SMB/NFS/packet field carries that payload.\nAC:L - check_leaf_item() had no BTRFS_ROOT_REF_KEY/BTRFS_ROOT_BACKREF_KEY case, so btrfs_check_leaf() accepted a ROOT_BACKREF whose item_size filled the leaf (~BTRFS_LEAF_DATA_SIZE). _btrfs_ioctl_get_subvol_info() then copied item_size-sizeof(struct btrfs_root_ref) into name[256] on every ioctl; the attacker fully controls that image.\nPR:L - btrfs_ioctl() dispatches BTRFS_IOC_GET_SUBVOL_INFO and BTRFS_IOC_INO_LOOKUP_USER with no capable() check. btrfs_fs_type has no FS_USERNS_MOUNT, so the severe case is an unprivileged session user whose USB/loop btrfs image is mounted by udisks2/polkit, then opens any fd in that subvolume and issues the ioctl.\nUI:N - The attacker crafts the ROOT_BACKREF, has that local image mounted, and themselves calls BTRFS_IOC_GET_SUBVOL_INFO (or BTRFS_IOC_INO_LOOKUP_USER, which copies the same item via btrfs_search_path_in_tree_user()) on their own fd. Automount of that local/removable image is not a separate victim action once AV is Local.\nS:U - The overflow is in the host kernel\u0027s kzalloc\u0027d btrfs_ioctl_get_subvol_info_args (and ino_lookup_user args) while parsing tree_root ROOT_BACKREF/ROOT_REF items. No KVM/Xen guest-to-host, IOMMU, or sandbox boundary is crossed.\nC:H - _btrfs_ioctl_get_subvol_info() and btrfs_search_path_in_tree_user() call read_extent_buffer() with a length taken from the on-disk item_size into name[BTRFS_VOL_NAME_MAX+1] (256 bytes). That out-of-bounds write of attacker-chosen leaf bytes into adjacent slab is a kernel-memory disclosure primitive.\nI:H - The same unbounded read_extent_buffer() into the 256-byte name[] of the kzalloc\u0027d ioctl args overwrites neighboring heap objects with attacker-controlled ROOT_BACKREF payload, which is sufficient for an arbitrary kernel write and control-flow hijacking.\nA:H - Copying a leaf-sized ROOT_BACKREF past btrfs_ioctl_get_subvol_info_args.name[256], or writing args-\u003ename[item_len]=\u0027\\0\u0027 in btrfs_search_path_in_tree_user() with that huge item_len, oopses or panics the kernel on the slab out-of-bounds access."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-03T10:58:06.771Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/1370badf6b823ce3cde39a65f46f9e5dc7b4bf43"
},
{
"url": "https://git.kernel.org/stable/c/ba6c4fc662853f6662e4db060cf88ee994053e21"
},
{
"url": "https://git.kernel.org/stable/c/9154542070ca7eadb3c764a882f39a127677854b"
},
{
"url": "https://git.kernel.org/stable/c/74f577c722c99248d804eca18e7de7c5e47549d7"
},
{
"url": "https://git.kernel.org/stable/c/0af37c217edf15fa21dac1c40822086df356c6bb"
}
],
"title": "btrfs: tree-checker: validate names in ROOT_REF and ROOT_BACKREF",
"x_generator": {
"engine": "bippy-1.2.0"
}
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"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-97415",
"datePublished": "2026-09-24T16:03:22.780Z",
"dateReserved": "2026-09-24T14:53:16.867Z",
"dateUpdated": "2026-10-03T10:58:06.771Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-97415",
"date": "2026-11-11",
"epss": "0.00131",
"percentile": "0.02777"
},
"microsoft_vex": {
"current_release_date": "2026-10-22T01:11:40.000Z",
"cve": "CVE-2026-97415",
"id": "msrc_CVE-2026-97415",
"initial_release_date": "2026-09-28T00:30:52.000Z",
"product_status:fixed": "1",
"product_status:known_affected": "1",
"product_status:under_investigation": "1",
"source": "Microsoft CSAF VEX",
"status": "final",
"title": "btrfs: tree-checker: validate names in ROOT_REF and ROOT_BACKREF",
"url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-97415.json",
"version": "4"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/btrfs/ioctl.c",
"fs/btrfs/tree-checker.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"status": "affected",
"version": "b64ec075bded2b30bcd90af5aa5256d2237c885d",
"versionType": "git"
},
{
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{
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},
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"status": "affected",
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"versionType": "git"
},
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{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"status": "affected",
"version": "4.18"
},
{
"lessThan": "4.18",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.189",
"versionType": "semver"
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{
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"status": "unaffected",
"version": "6.6.158",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.111",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.53",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: tree-checker: validate names in ROOT_REF and ROOT_BACKREF\n\nROOT_REF and ROOT_BACKREF items contain a struct btrfs_root_ref followed\nby the subvolume name. Several readers assume that this layout is already\nvalid and then use the on-disk name length directly. A corrupted item can\ntherefore make those readers address bytes outside the item, and\nBTRFS_IOC_GET_SUBVOL_INFO can copy too many bytes into its fixed-size UAPI\nname buffer.\n\nValidate ROOT_REF and ROOT_BACKREF items in tree-checker before any reader\nuses them. Reject records that do not contain a non-empty name, whose\nname_len does not exactly describe the remaining item payload, or whose\nname exceeds BTRFS_NAME_LEN.\n\nFor BTRFS_IOC_GET_SUBVOL_INFO, copy only the validated on-disk name_len\ninstead of deriving the copy length from the item size. The ioctl result is\nzeroed when allocated. That leaves the existing trailing zero byte\nuntouched."
}
],
"id": "CVE-2026-97415",
"lastModified": "2026-10-03T11:17:53.457",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-09-24T17:17:19.223",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/0af37c217edf15fa21dac1c40822086df356c6bb"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/1370badf6b823ce3cde39a65f46f9e5dc7b4bf43"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/74f577c722c99248d804eca18e7de7c5e47549d7"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/9154542070ca7eadb3c764a882f39a127677854b"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/ba6c4fc662853f6662e4db060cf88ee994053e21"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-11-06T02:18:21+00:00",
"cve": "CVE-2026-97415",
"id": "CVE-2026-97415",
"initial_release_date": "2026-09-24T00:00:00+00:00",
"product_status:known_affected": "43",
"product_status:known_not_affected": "157",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: btrfs: tree-checker: validate names in ROOT_REF and ROOT_BACKREF",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97415.json",
"version": "3"
}
}
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
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They have not been verified by an analyst and are provided for guidance only.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
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