CVE-2026-90217 (GCVE-0-2026-90217)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:07 – Updated: 2026-09-18 17:53
VLAI
Title
bpf: Compare iterator types during state pruning
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Compare iterator types during state pruning An iterator stack slot can be MEM_RCU or PTR_UNTRUSTED. These states must not be equal, or the verifier can prune an unsafe path. Compare the pointer type for STACK_ITER slots.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: dfab99df147b0d364f0c199f832ff2aedfb2265a , < 6424b9cde9edc7f2098115bbfd1ee3d84a958380 (git)
Affected: dfab99df147b0d364f0c199f832ff2aedfb2265a , < 83608e303b95d07afba1c15da0b5d9e513c2f15a (git)
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Linux Linux Affected: 6.7
Unaffected: 0 , < 6.7 (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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          "product": "Linux",
          "programFiles": [
            "kernel/bpf/states.c"
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              "version": "6.7"
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              "status": "unaffected",
              "version": "0",
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                  "vulnerable": true
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Compare iterator types during state pruning\n\nAn iterator stack slot can be MEM_RCU or PTR_UNTRUSTED. These states\nmust not be equal, or the verifier can prune an unsafe path.\n\nCompare the pointer type for STACK_ITER slots."
        }
      ],
      "metrics": [
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            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:L - The attacker-controlled input is the BPF instruction stream copied in bpf_prog_load() from bpf(2) BPF_PROG_LOAD (__sys_bpf). bpf_check() then stacksafe() treats STACK_ITER slots with MEM_RCU and PTR_UNTRUSTED as equal; that bytecode is local syscall input, not a remote protocol payload.\nAC:L - The attacker authors both verifier paths as in iter_tasks_rcu_state_pruning: bpf_iter_task_new under bpf_rcu_read_lock, then a bpf_get_prandom_u32 branch that nested-lock/unlock (MEM_RCU) or unlock/relock (PTR_UNTRUSTED) before bpf_iter_task_next. Both sides and the branch are attacker-controlled; no victim timing is required.\nPR:L - add_subprog_and_kfunc() rejects kfunc calls unless env-\u003ebpf_capable. bpf_iter_task_new and bpf_iter_css_new are kfuncs; BPF_PROG_TYPE_SYSCALL (always sleepable) needs only bpf_token_capable(CAP_BPF). bpf_token_capable() uses ns_capable() on a delegated token userns, so this is not init-namespace root.\nUI:N - The attacker loads the crafted sleepable program with BPF_PROG_LOAD and executes it via BPF_PROG_TEST_RUN (bpf_prog_test_run_syscall) or by attaching their own fentry.s; no other user must mount a filesystem, open a file, or cooperate.\nS:U - A pruned bpf_iter_task_next() walks host task_struct lists in the same kernel that loaded the program. That is in-kernel use-after-free and privilege escalation, not a KVM/Xen guest-to-host escape or IOMMU bypass.\nC:H - After the pruned unlock/relock gap, bpf_iter_task_next() returns kit-\u003epos from bpf_iter_task_kern, a task_struct * that may already have been RCU-freed. The program can read BTF fields of that dangling pointer, so the UAF is an arbitrary kernel disclosure.\nI:H - bpf_iter_task_next() then calls next_task()/__next_thread() (list_entry_rcu on tasks.next and thread_node) using the dangling kit-\u003epos. Walking attacker-reclaimed task_struct list nodes is a kernel write primitive; UAF and iterator type confusion are Integrity High.\nA:H - Using the untrusted STACK_ITER after the RCU gap makes next_task() or css_next_descendant_*() dereference a freed task_struct or cgroup_subsys_state, causing a kernel oops or panic even when the UAF is not fully exploited."
            }
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      "providerMetadata": {
        "dateUpdated": "2026-09-18T17:53:48.672Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/6424b9cde9edc7f2098115bbfd1ee3d84a958380"
        },
        {
          "url": "https://git.kernel.org/stable/c/83608e303b95d07afba1c15da0b5d9e513c2f15a"
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      ],
      "title": "bpf: Compare iterator types during state pruning",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90217",
    "datePublished": "2026-09-17T16:07:29.409Z",
    "dateReserved": "2026-09-11T19:38:34.793Z",
    "dateUpdated": "2026-09-18T17:53:48.672Z",
    "state": "PUBLISHED"
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      "date": "2026-09-25",
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      "percentile": "0.05085"
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                "programFiles": [
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Compare iterator types during state pruning\n\nAn iterator stack slot can be MEM_RCU or PTR_UNTRUSTED. These states\nmust not be equal, or the verifier can prune an unsafe path.\n\nCompare the pointer type for STACK_ITER slots."
          }
        ],
        "id": "CVE-2026-90217",
        "lastModified": "2026-09-18T18:17:46.850",
        "metrics": {
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                "attackVector": "LOCAL",
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                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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