{ "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": "2026-08-23T12:46:41.836Z" }, "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." } ], "metrics": [ { "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": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/locking/spinlock_rt.c" ], "versions": [ { "version": "0f383b6dc96e976dfbf2721b0bf10bd96103b341", "lessThan": "af28d801cd2db4cc7378554499bd4a5d84a5517e", "status": "affected", "versionType": "git" }, { "version": "0f383b6dc96e976dfbf2721b0bf10bd96103b341", "lessThan": "9d1fcd64ab81200e02b7a6db5eb1da8e244e8289", "status": "affected", "versionType": "git" }, { "version": "0f383b6dc96e976dfbf2721b0bf10bd96103b341", "lessThan": "3cfaac77b3c32ac3940df28866de263c3f45d24c", "status": "affected", "versionType": "git" }, { "version": "0f383b6dc96e976dfbf2721b0bf10bd96103b341", "lessThan": "1f0d56d3f1e88f20f6e46109402f8c15d59bac37", "status": "affected", "versionType": "git" }, { "version": "0f383b6dc96e976dfbf2721b0bf10bd96103b341", "lessThan": "633cadbc0b8323f5cc140a285d2432089dbb534e", "status": "affected", "versionType": "git" }, { "version": "0f383b6dc96e976dfbf2721b0bf10bd96103b341", "lessThan": "83f9fb561c1c3917e19f95523dd933c7d30291aa", "status": "affected", "versionType": "git" }, { "version": "0f383b6dc96e976dfbf2721b0bf10bd96103b341", "lessThan": "89038cc87d80c77e7aa6f42a64b2573b74af339f", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/locking/spinlock_rt.c" ], "versions": [ { "version": "5.15", "status": "affected" }, { "version": "0", "lessThan": "5.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.217", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.184", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.148", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.101", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "5.15.217" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.1.184" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.6.148" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.12.101" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/af28d801cd2db4cc7378554499bd4a5d84a5517e" }, { "url": "https://git.kernel.org/stable/c/9d1fcd64ab81200e02b7a6db5eb1da8e244e8289" }, { "url": "https://git.kernel.org/stable/c/3cfaac77b3c32ac3940df28866de263c3f45d24c" }, { "url": "https://git.kernel.org/stable/c/1f0d56d3f1e88f20f6e46109402f8c15d59bac37" }, { "url": "https://git.kernel.org/stable/c/633cadbc0b8323f5cc140a285d2432089dbb534e" }, { "url": "https://git.kernel.org/stable/c/83f9fb561c1c3917e19f95523dd933c7d30291aa" }, { "url": "https://git.kernel.org/stable/c/89038cc87d80c77e7aa6f42a64b2573b74af339f" } ], "title": "locking/rt: Fix the incorrect RCU protection in rt_spin_unlock()", "x_generator": { "engine": "bippy-1.2.0" } } } }