230 lines
13 KiB
JSON
230 lines
13 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-2026-53341",
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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": "2026-06-09T07:44:35.399Z",
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"datePublished": "2026-07-01T13:32:22.873Z",
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"dateUpdated": "2026-10-19T20:07:43.543Z"
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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": "2026-08-05T12:35:02.388Z"
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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\nfhandle: fix UAF due to unlocked ->mnt_ns read in may_decode_fh()\n\nmay_decode_fh() accesses mount::mnt_ns without holding any locks; that\nmeans the mount can concurrently be unmounted, and the mnt_namespace can\nconcurrently be freed after an RCU grace period.\n\nThis race can happens as follows, assuming that the mount point was\ncreated by open_tree(..., OPEN_TREE_CLONE):\n\nthread 1 thread 2 RCU\n __do_sys_open_by_handle_at\n do_handle_open\n handle_to_path\n may_decode_fh\n is_mounted\n [mount::mnt_ns access]\n [mount::mnt_ns access]\n__do_sys_close\n fput_close_sync\n __fput\n dissolve_on_fput\n umount_tree\n class_namespace_excl_destructor\n namespace_unlock\n free_mnt_ns\n mnt_ns_tree_remove\n call_rcu(mnt_ns_release_rcu)\n mnt_ns_release_rcu\n mnt_ns_release\n kfree\n [mnt_namespace::user_ns access] **UAF**\n\nFix it by taking rcu_read_lock() around the mount::mnt_ns access, like\nin __prepend_path().\nAdditionally, document the semantics of mount::mnt_ns, and use WRITE_ONCE()\nfor writers that can race with lockless readers.\n\nThis bug is unreachable unless one of the following is set:\n\n - CONFIG_PREEMPTION\n - CONFIG_RCU_STRICT_GRACE_PERIOD\n\nbecause it requires an RCU grace period to happen during a syscall without\nan explicit preemption.\n\nThis doesn't seem to have interesting security impact; worst-case, it could\nleak the result of an integer comparison to userspace (from the level\ncheck in cap_capable()), cause an endless loop, or crash the kernel by\ndereferencing an invalid address."
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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 vulnerable code is reached through local syscalls, primarily `open_by_handle_at()` racing with close/fput of a mount file created by `open_tree(..., OPEN_TREE_CLONE)`. There is no network or adjacent attack path.\nAC:L - The attacker can control both sides of the race by running concurrent local threads that call `open_by_handle_at()` and close the cloned mount file. Although the bug requires preemption or strict RCU grace periods, those are reasonable kernel configurations and the race is attacker-driven.\nPR:L - The path requires namespace-relative capabilities such as `CAP_SYS_ADMIN` and `CAP_DAC_READ_SEARCH`, which an unprivileged local user can obtain inside a user namespace on systems where unprivileged user namespaces are enabled. It does not require real init-namespace root.\nUI:N - No victim action is required; the attacker directly invokes the relevant syscalls and controls the racing threads. The mount clone, handle input, and close operation are all attacker initiated.\nS:U - The vulnerability affects kernel VFS/mount namespace state within the same security authority. It is a local kernel memory-safety issue, not a VM escape or cross-scope boundary bypass.\nC:H - The bug is a kernel use-after-free of `struct mnt_namespace`, followed by dereferencing reclaimed memory through `mnt_ns->user_ns` and capability-walk fields. Per the higher-severity rule for kernel UAFs, this is scored as high confidentiality impact.\nI:H - The immediate operation is a stale read in an authorization check, but reclaimed kernel heap contents can influence capability-check control flow and UAFs are treated as potentially exploitable memory corruption. Under the required uncertainty rule, integrity impact is high.\nA:H - The stale `mnt_namespace` dereference can crash the kernel, loop indefinitely, or otherwise destabilize the system. A local attacker can repeatedly trigger the race, so availability impact is high."
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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/fhandle.c",
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"fs/mount.h",
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"fs/namespace.c"
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],
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"status": "affected",
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"versionType": "git"
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},
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"lessThan": "32138633e51e6db59e474765cf93268c92b42888",
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"status": "affected",
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"status": "affected",
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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/fhandle.c",
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"fs/mount.h",
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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": "6.11",
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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": "6.11",
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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": "6.12.95",
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"lessThanOrEqual": "6.12.*",
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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": "6.18.36",
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"lessThanOrEqual": "6.18.*",
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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": "7.0.13",
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"lessThanOrEqual": "7.0.*",
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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": "7.1",
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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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"operator": "OR",
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"versionStartIncluding": "6.11",
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/15ea8dc42a02259d49dee38a658d40f60fcd75ed"
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},
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{
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"url": "https://git.kernel.org/stable/c/32138633e51e6db59e474765cf93268c92b42888"
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},
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{
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"url": "https://git.kernel.org/stable/c/a8ed2c29fcfdac78db96c9da4e659c8a513f2a94"
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},
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{
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"url": "https://git.kernel.org/stable/c/40ab6644b99685755f740b872c00ef40d9aa870e"
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}
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],
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"title": "fhandle: fix UAF due to unlocked ->mnt_ns read in may_decode_fh()",
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"x_generator": {
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"engine": "bippy-1.2.0"
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"adp": [
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{
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"metrics": [
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"other": {
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"type": "ssvc",
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"content": {
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"id": "CVE-2026-53341",
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"role": "CISA Coordinator",
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"options": [
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{
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"Exploitation": "none"
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},
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{
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"Automatable": "no"
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},
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{
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"Technical Impact": "total"
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}
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],
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"version": "2.0.3",
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"timestamp": "2026-10-16T15:28:32.016897Z"
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}
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}
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}
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],
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"problemTypes": [
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{
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"descriptions": [
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{
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"lang": "en",
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"type": "CWE",
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"cweId": "CWE-416",
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"description": "CWE-416 Use After Free"
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}
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]
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}
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],
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"title": "CISA ADP Vulnrichment",
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"providerMetadata": {
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"shortName": "CISA-ADP",
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"dateUpdated": "2026-10-19T20:07:43.543Z"
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}
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}
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} |