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vuln-cve/data/2026/72xxx/CVE-2026-72069.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-72069",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-08-09T03:40:39.903Z",
"datePublished": "2026-08-15T05:52:21.752Z",
"dateUpdated": "2026-10-19T21:19:26.463Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-08-23T12:46:41.836Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlocking/rt: Fix the incorrect RCU protection in rt_spin_unlock()\n\nrt_spin_unlock() releases the RCU protection before unlocking the\nlock. That opens the door for the following UAF scenario:\n\n T1\t\t\t\t\tT2\n spin_lock(&p->lock);\t\trcu_read_lock();\n invalidate(p);\t\t\tp = rcu_dereference(ptr);\n rcu_assign_pointer(ptr, NULL);\tif (!p) return;\n spin_unlock(&p->lock);\t\tspin_lock(&p->lock)\n \t\t\t\t lock(&lock->lock);\n\t\t\t\t rcu_read_lock();\n kfree_rcu(p);\t\t\trcu_read_unlock();\n\t\t\t\t....\n\t\t\t\tspin_unlock(&p->lock)\n\t\t\t\t rcu_read_unlock(); // Ends grace period\n rcu_do_batch()\n kfree(p);\n\t\t\t UAF ->\t rt_mutex_cmpxchg_release(&lock->lock...)\n\nRegular spinlocks keep preemption disabled accross the unlock operation,\nwhich provides full RCU protection, but the RT substitution fails to\nresemble that. Same applies for the rwlock substitution.\n\nMove the rcu_read_unlock() invocation past the unlock operations to match\nthe non-RT semantics. This makes it asymmetric vs. rt_xxx_lock(), but\nthat's harmless as the caller needs to hold RCU read lock across the lock\noperation. The migrate_enable() call stays before the unlock operation\nbecause there is no per CPU operation in the unlock path which would\nrequire migration to be kept disabled."
}
],
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{
"cvssV3_1": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 9.8,
"baseSeverity": "CRITICAL"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - On CONFIG_PREEMPT_RT, every spin_unlock() is substituted by rt_spin_unlock(); network subsystems such as netfilter xt_hashlimit process inbound packets through hashlimit_mt_common(), spin_lock/unlock on RCU-protected dsthash_ent objects concurrently freed via call_rcu by GC—the exact embedded-spinlock UAF pattern from the fix.\nAC:L - The bug is a cross-CPU race where rt_spin_unlock() calls rcu_read_unlock() before releasing the rtmutex, ending the RCU grace period while still dereferencing the lock; syzbot triggered this reliably on PREEMPT_RT via concurrent unlinkat and dentry teardown, and attackers control both sides with parallel syscalls or packet/GC load.\nPR:N - Remote attackers need no account, capability, or authentication to send packets that hit deployed hashlimit rules on internet-facing PREEMPT_RT gateways; the proven syzbot unlinkat path needs only directory write permission (PR:L), but PR:N reflects the highest-severity unauthenticated network packet scenario.\nUI:N - No victim interaction is required; the attacker drives the race through their own concurrent filesystem syscalls (syzbot: unlinkat racing __fput/dentry_kill) or sustained inbound traffic overlapping netfilter GC, without needing another user to open files or mount filesystems.\nS:U - The UAF corrupts kernel slab memory containing embedded spinlock/rtmutex fields and enables privilege escalation within the same kernel security authority; it does not inherently cross VM/guest, container sandbox, or IOMMU hardware isolation boundaries.\nC:H - Syzbot reported KASAN slab-use-after-free Read in rt_mutex_slowunlock during spin_unlock on a freed dentry in shrink_dcache_tree; the systemic UAF lets attackers read freed objects (dentry, dsthash_ent, etc.) after premature RCU grace-period completion, enabling kernel pointer and memory disclosure.\nI:H - UAF on embedded rtmutex fields inside freed slab objects (dentry->d_lock per syzbot) permits heap grooming and reallocation of attacker-controlled data, providing standard kernel heap corruption primitives for arbitrary write and control-flow hijack beyond the immediate crash.\nA:H - Syzbot hit KASAN slab-use-after-free causing kernel fault in shrink_dcache_tree via rt_spin_unlock on PREEMPT_RT; the bug can oops/panic any RT kernel whenever spin_unlock races RCU-deferred free of the containing object, enabling repeatable denial of service via concurrent VFS or netfilter operations."
}
]
}
],
"affected": [
{
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"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"kernel/locking/spinlock_rt.c"
],
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{
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"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
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],
"versions": [
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"version": "5.15",
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},
{
"version": "0",
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"status": "unaffected",
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},
{
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"lessThanOrEqual": "5.15.*",
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{
"version": "6.1.184",
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},
{
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"lessThanOrEqual": "6.6.*",
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},
{
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"lessThanOrEqual": "6.12.*",
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},
{
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"lessThanOrEqual": "6.18.*",
"status": "unaffected",
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},
{
"version": "7.1.5",
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
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},
{
"version": "7.2",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
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"nodes": [
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"operator": "OR",
"negate": false,
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"references": [
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"url": "https://git.kernel.org/stable/c/af28d801cd2db4cc7378554499bd4a5d84a5517e"
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{
"url": "https://git.kernel.org/stable/c/9d1fcd64ab81200e02b7a6db5eb1da8e244e8289"
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{
"url": "https://git.kernel.org/stable/c/89038cc87d80c77e7aa6f42a64b2573b74af339f"
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"title": "locking/rt: Fix the incorrect RCU protection in rt_spin_unlock()",
"x_generator": {
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"adp": [
{
"metrics": [
{
"other": {
"type": "ssvc",
"content": {
"id": "CVE-2026-72069",
"role": "CISA Coordinator",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "total"
}
],
"version": "2.0.3",
"timestamp": "2026-10-16T15:51:20.973593Z"
}
}
}
],
"problemTypes": [
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"descriptions": [
{
"lang": "en",
"type": "CWE",
"cweId": "CWE-416",
"description": "CWE-416 Use After Free"
}
]
}
],
"title": "CISA ADP Vulnrichment",
"providerMetadata": {
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"dateUpdated": "2026-10-19T21:19:26.463Z"
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}