CVE-2026-93045 (GCVE-0-2026-93045)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:10 – Updated: 2026-09-18 17:55
VLAI
Title
bpf: Reject arena frees below the arena base
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject arena frees below the arena base bpf_arena_free_pages() accepts scalar arena addresses. The runtime masks the address to the low 32 bits and reconstructs a full user address from the arena base before returning the range to the arena free tree. When the scalar value is below the low 32 bits of the arena base, full_uaddr falls below user_vm_start. The existing upper-end clipping then turns this into an out-of-range free-tree offset. A later allocation can reuse that offset and return an address below the arena mapping. Reject such frees before computing the clipped range.
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: 317460317a02a1af512697e6e964298dedd8a163 , < 90453eaf8f14e7be0ab03983f2a93aeb6b990a58 (git)
Affected: 317460317a02a1af512697e6e964298dedd8a163 , < a968dffa5ab3c74d2ebb3a6233bf8b843f0bfc20 (git)
Affected: 317460317a02a1af512697e6e964298dedd8a163 , < 8a08635656037aee9c12231ed384449c4ffb1a93 (git)
Affected: 317460317a02a1af512697e6e964298dedd8a163 , < b5a71cb2db6d84ac0042549dcec266b18429d41e (git)
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Linux Linux Affected: 6.9
Unaffected: 0 , < 6.9 (semver)
Unaffected: 6.12.110 , ≤ 6.12.* (semver)
Unaffected: 6.18.52 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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Show details on NVD website
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/arena.c"
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          "vendor": "Linux",
          "versions": [
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              "version": "6.9"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.12.110",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
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                  "versionStartIncluding": "6.9",
                  "vulnerable": true
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.52",
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                  "vulnerable": true
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject arena frees below the arena base\n\nbpf_arena_free_pages() accepts scalar arena addresses. The runtime\nmasks the address to the low 32 bits and reconstructs a full user\naddress from the arena base before returning the range to the arena\nfree tree.\n\nWhen the scalar value is below the low 32 bits of the arena base,\nfull_uaddr falls below user_vm_start. The existing upper-end clipping\nthen turns this into an out-of-range free-tree offset. A later\nallocation can reuse that offset and return an address below the arena\nmapping.\n\nReject such frees before computing the clipped range."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "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": [
            {
              "lang": "en",
              "value": "AV:L - The attacker-controlled input is the scalar ptr passed to bpf_arena_free_pages() from a locally loaded BPF program after bpf(BPF_MAP_CREATE) of BPF_MAP_TYPE_ARENA, mmap() of that map, bpf(BPF_PROG_LOAD), and bpf(BPF_PROG_TEST_RUN) (e.g. BPF_PROG_TYPE_SYSCALL). The below-base address is not carried in a network protocol message.\nAC:L - The attacker chooses the scalar whose low 32 bits are below (u32)arena-\u003euser_vm_start and the page_cnt passed to bpf_arena_free_pages(); compute_pgoff() then underflows and range_tree_set() records that offset deterministically. No race, victim state, or rare non-default config is required on JITs that implement bpf_jit_supports_arena() (x86_64/arm64).\nPR:L - map_create() requires bpf_token_capable(CAP_BPF) for BPF_MAP_TYPE_ARENA, and check_map_prog_compatibility() additionally requires CAP_PERFMON (env-\u003eallow_ptr_leaks) before a program may reference the arena. Those caps are delegable through BPF tokens into a user namespace rather than requiring init-namespace root.\nUI:N - The attacker creates their own arena map, mmap()s it so user_vm_start is set, loads their own program that calls bpf_arena_free_pages() with a below-base scalar, and runs it via BPF_PROG_TEST_RUN. No separate victim mount, open, or other interaction is required.\nS:U - arena_free_pages() corrupts the arena range_tree and kernel PTEs of the same host kernel that loaded the program. This is in-kernel memory unsafety, not a KVM/Xen guest-to-host escape or IOMMU/DMA boundary cross.\nC:H - With a below-base scalar and a large page_cnt, arena_free_pages() clips uaddr_end to user_vm_end so apply_to_existing_page_range() walks from kern_vm_start+uaddr32 across in-use arena PTEs and __free_page()s those pages while compute_pgoff() records a wrapped offset, leaving a page UAF that can disclose kernel memory.\nI:H - The same clipped free desynchronizes PTEs from the range_tree, and zap_pages() calls zap_vma_range() with full_uaddr below vma-\u003evm_start, clearing mm PTEs outside the arena VMA. A later bpf_arena_alloc_pages() reuses the out-of-range offset via range_tree_find(), giving an exploitable page-reuse write primitive.\nA:H - Accessing a below-base pointer with a negative LDX/STX off faults below kern_vm_start, where bpf_arena_handle_page_fault() refuses recovery and oopses; zap_vma_range() also VM_WARN_ON_ONCE()s for a range outside the arena VMA, and the UAF of freed arena pages can panic the kernel."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-18T17:55:45.700Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/b5a71cb2db6d84ac0042549dcec266b18429d41e"
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      "title": "bpf: Reject arena frees below the arena base",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93045",
    "datePublished": "2026-09-17T16:10:36.988Z",
    "dateReserved": "2026-09-17T15:57:05.658Z",
    "dateUpdated": "2026-09-18T17:55:45.700Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-09-29",
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject arena frees below the arena base\n\nbpf_arena_free_pages() accepts scalar arena addresses. The runtime\nmasks the address to the low 32 bits and reconstructs a full user\naddress from the arena base before returning the range to the arena\nfree tree.\n\nWhen the scalar value is below the low 32 bits of the arena base,\nfull_uaddr falls below user_vm_start. The existing upper-end clipping\nthen turns this into an out-of-range free-tree offset. A later\nallocation can reuse that offset and return an address below the arena\nmapping.\n\nReject such frees before computing the clipped range."
          }
        ],
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        "lastModified": "2026-09-18T18:18:19.097",
        "metrics": {
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                "confidentialityImpact": "HIGH",
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                "userInteraction": "NONE",
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              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-09-17T17:17:57.743",
        "references": [
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        "vulnStatus": "Received"
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    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-22T16:25:47Z",
      "cve": "CVE-2026-93045",
      "id": "CVE-2026-93045",
      "initial_release_date": "2026-09-22T16:25:47Z",
      "product_status:known_affected": "29",
      "product_status:known_not_affected": "318",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-93045",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-93045.json",
      "version": "2"
    }
  }
}



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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.

Sightings

Author Source Type Date Other

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.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.