CVE-2026-64015 (GCVE-0-2026-64015)
Vulnerability from cvelistv5
Published
2026-07-19 15:39
Modified
2026-08-05 12:38
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: security/keys: fix missed RCU read section on lookup Nicholas Carlini reports that the keyring code calls assoc_array_find() in find_key_to_update() without holding the RCU read lock, while the assoc_array_gc() code really is designed around removing the node from the tree and then freeing it after an RCU grace-period. The regular key handling doesn't see this because holding the keyring semaphore hides any lifetime issues, but the persistent key handling uses a different model. Instead of extending the keyring locking, just do the simple RCU locking that the assoc_array was designed for.
References
Impacted products
Vendor Product Version
Linux Linux Version: b2a4df200d570b2c33a57e1ebfa5896e4bc81b69
Version: b2a4df200d570b2c33a57e1ebfa5896e4bc81b69
Version: b2a4df200d570b2c33a57e1ebfa5896e4bc81b69
Version: b2a4df200d570b2c33a57e1ebfa5896e4bc81b69
Version: b2a4df200d570b2c33a57e1ebfa5896e4bc81b69
Version: b2a4df200d570b2c33a57e1ebfa5896e4bc81b69
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsecurity/keys: fix missed RCU read section on lookup\n\nNicholas Carlini reports that the keyring code calls assoc_array_find()\nin find_key_to_update() without holding the RCU read lock, while the\nassoc_array_gc() code really is designed around removing the node from\nthe tree and then freeing it after an RCU grace-period.\n\nThe regular key handling doesn\u0027t see this because holding the keyring\nsemaphore hides any lifetime issues, but the persistent key handling\nuses a different model.\n\nInstead of extending the keyring locking, just do the simple RCU locking\nthat the assoc_array was designed for."
        }
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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              "value": "AV:L - The bug is reached only through find_key_to_update() on the persistent keyring register, which is invoked from keyctl_get_persistent() via the keyctl(2) syscall. There is no network, adjacent-radio, or physical-device path to this code.\nAC:L - Exploitation is a race between assoc_array_find() and assoc_array_gc() on the .persistent_register keyring; the attacker controls both sides by repeatedly calling KEYCTL_GET_PERSISTENT (including from multiple threads) while driving key expiry/GC via keyctl timeouts or natural garbage collection. Per kernel guidance, attacker-controlled races are AC:L.\nPR:L - Any unprivileged local user who can invoke keyctl() can call KEYCTL_GET_PERSISTENT for their own UID (-1) with a writable destination keyring (e.g., session keyring). No real-root or CAP_SETUID capability is required for the vulnerable lookup path; this remains PR:L even inside user namespaces.\nUI:N - Exploitation requires only the attacker\u0027s own keyctl syscalls and does not depend on any victim user action such as mounting a filesystem or opening a file.\nS:U - Impact is confined to kernel memory corruption and privilege escalation within the same kernel security domain; it does not cross a VM, container, or IOMMU boundary on its own.\nC:H - assoc_array_find() is documented to require an RCU read lock, but the persistent-keyring path called it without one while assoc_array_gc() frees tree nodes via call_rcu(), yielding a use-after-free on assoc_array nodes/leaves. UAF on kernel heap objects can be turned into arbitrary kernel memory reads.\nI:H - The freed assoc_array nodes can be reallocated and corrupted through concurrent GC versus lookup, providing a standard kernel heap UAF primitive that can be developed into arbitrary write or code-execution primitives.\nA:H - Dereferencing RCU-freed assoc_array tree nodes during lookup can cause kernel oops/panic from invalid pointer access, and UAF exploitation commonly destabilizes or crashes the kernel even when full exploitation is not attempted."
            }
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      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:38:12.353Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/4c5d407ba3ff7f30561ff73ba1b07ed70c864edc"
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        {
          "url": "https://git.kernel.org/stable/c/cefa4265b11176c897a7d9e8e54d89e3701c5584"
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          "url": "https://git.kernel.org/stable/c/50bb3435a5e627bfbdc52eb4536f49f88b3486b8"
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          "url": "https://git.kernel.org/stable/c/66288dcadf80974436250e9f70ed848836b835b5"
        },
        {
          "url": "https://git.kernel.org/stable/c/43a1e3744548e6fd85873e6fb43e293eb4010694"
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      "title": "security/keys: fix missed RCU read section on lookup",
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64015",
    "datePublished": "2026-07-19T15:39:10.557Z",
    "dateReserved": "2026-07-19T07:54:57.027Z",
    "dateUpdated": "2026-08-05T12:38:12.353Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2"
}


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