138 lines
8.3 KiB
JSON
138 lines
8.3 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2025-39717",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2025-04-16T07:20:57.117Z",
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"datePublished": "2025-09-05T17:21:24.528Z",
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"dateUpdated": "2026-08-05T12:04:48.428Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-08-05T12:04:48.428Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nopen_tree_attr: do not allow id-mapping changes without OPEN_TREE_CLONE\n\nAs described in commit 7a54947e727b ('Merge patch series \"fs: allow\nchanging idmappings\"'), open_tree_attr(2) was necessary in order to\nallow for a detached mount to be created and have its idmappings changed\nwithout the risk of any racing threads operating on it. For this reason,\nmount_setattr(2) still does not allow for id-mappings to be changed.\n\nHowever, there was a bug in commit 2462651ffa76 (\"fs: allow changing\nidmappings\") which allowed users to bypass this restriction by calling\nopen_tree_attr(2) *without* OPEN_TREE_CLONE.\n\ncan_idmap_mount() prevented this bug from allowing an attached\nmountpoint's id-mapping from being modified (thanks to an is_anon_ns()\ncheck), but this still allows for detached (but visible) mounts to have\ntheir be id-mapping changed. This risks the same UAF and locking issues\nas described in the merge commit, and was likely unintentional."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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"baseScore": 7.8,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:L - The vulnerability is reached purely through local syscalls — `open_tree(2)` to create a detached mount and `open_tree_attr(2)` to replace its idmapping. There is no remote or adjacent-network path to fs/namespace.c mount attribute handling.\nAC:L - The attacker controls both sides of the race entirely: one thread calls `open_tree_attr()` to free the old `struct mnt_idmap` while attacker-spawned threads hammer `openat()`/`statx()`/`open_tree(OPEN_TREE_CLONE)` on the same detached-mount fd, and the replace can be repeated in a loop with a heap spray of the kmalloc-cg-192 slab.\nPR:L - Only an unprivileged local user is required — `unshare -Urm` grants CAP_SYS_ADMIN over both the new mount namespace (satisfying `may_mount()`) and over the superblock's `s_user_ns` (satisfying `can_idmap_mount()`) for a self-mounted tmpfs or fuse filesystem, both of which carry `FS_USERNS_MOUNT | FS_ALLOW_IDMAP`.\nUI:N - The attacker performs every step — creating the detached mount, applying the first idmapping, and racing the replacement — within its own processes. No victim action of any kind is needed.\nS:U - The freed object and all corrupted state live in the kernel's own memory; the impact is confined to the kernel security authority with no crossing of a VM, IOMMU, or hypervisor boundary.\nC:H - This is a use-after-free on a heap object whose contents directly determine mapped uid/gid values, so refilling the freed slot lets the attacker forge `uid_gid_map.forward` into an arbitrary kernel pointer that `bsearch()` dereferences, with the result observable via `stat()` — an arbitrary kernel memory read.\nI:H - `clone_mnt()`'s `mnt_idmap_get()` performs a `refcount_inc()` on the freed object, giving a write primitive into reclaimed heap memory, and the stale/forged idmapping also causes ownership and permission decisions to be made from attacker-influenced data.\nA:H - Dereferencing the freed `struct mnt_idmap` and its `kfree()`d extent arrays, plus refcount underflow and double-free on repeated replacement, reliably produce an oops or panic taking down the whole system."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/namespace.c"
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],
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"versions": [
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{
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"version": "2462651ffa76b87f9c2e4403ef6e6b89b703fb2f",
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"lessThan": "69dbdc711d9130136824e3830191a6afffa0a1f0",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "2462651ffa76b87f9c2e4403ef6e6b89b703fb2f",
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"lessThan": "9308366f062129d52e0ee3f7a019f7dd41db33df",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/namespace.c"
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],
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"versions": [
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{
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"version": "6.15",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "6.15",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.16.4",
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"lessThanOrEqual": "6.16.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.17",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.15",
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"versionEndExcluding": "6.16.4"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.15",
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"versionEndExcluding": "6.17"
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}
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]
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}
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/69dbdc711d9130136824e3830191a6afffa0a1f0"
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},
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{
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"url": "https://git.kernel.org/stable/c/9308366f062129d52e0ee3f7a019f7dd41db33df"
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}
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],
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"title": "open_tree_attr: do not allow id-mapping changes without OPEN_TREE_CLONE",
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"x_generator": {
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"engine": "bippy-1.2.0"
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} |