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CVE-2026-89579 (GCVE-0-2026-89579)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:44 – Updated: 2026-09-14 12:01
VLAI
Title
bpf: Harden bloom filter sizing and indexing on 32-bit kernels
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Harden bloom filter sizing and indexing on 32-bit kernels bloom_map_alloc() has two 32-bit-specific problems when the computed bitmap reaches the U32_MAX fallback case. First, BITS_TO_BYTES(U32_MAX) is evaluated with 32-bit arithmetic. The addition performed by DIV_ROUND_UP wraps, so the map allocates only the fixed-size bloom filter object while keeping bitset_mask == U32_MAX. Subsequent updates can then write past the allocated object. Second, fixing only the allocation size is not sufficient. The bloom hash is a u32, but set_bit() takes a signed long bit number and x86 test_bit() eventually feeds the index to variable_test_bit(long, ...). On 32-bit kernels, hashes in [0x80000000, U32_MAX] therefore become negative bit offsets. x86 bt/bts with a memory operand interpret those offsets relative to the supplied base, so a map with bitset_mask == U32_MAX can read or write before bloom->bitset even after allocating the full 512 MiB bitmap. Keep the U32_MAX fallback, but split each hash into a word pointer and an in-word bit number before calling test_bit() or set_bit(). The bitops argument is then always in [0, BITS_PER_LONG - 1], while BIT_WORD(h) still selects the intended word in the full bitmap. Compute the bitset size from (u64)bitset_mask + 1 before passing the final size to bpf_map_area_alloc(). This fixes the original under-allocation and keeps the allocated storage consistent with the addressable bitset. Exploitation note: local privilege escalation is possible on a 32-bit x86 kernel using the under-allocation bug from a binary with CAP_BPF.
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: 9330986c03006ab1d33d243b7cfe598a7a3c1baa , < a6183bc683f97f4317f7e84939ca7fff37c5688b (git)
Affected: 9330986c03006ab1d33d243b7cfe598a7a3c1baa , < 80551bf8912c42d1e3d55eec6fa3c40f306c3de8 (git)
Affected: 9330986c03006ab1d33d243b7cfe598a7a3c1baa , < 3b7a13eccfcf97714ffc1ca6aa663d66d4a30e29 (git)
Affected: 9330986c03006ab1d33d243b7cfe598a7a3c1baa , < 272fcb4ba6fab678db0eb966dc81c4c804bef64a (git)
Affected: 9330986c03006ab1d33d243b7cfe598a7a3c1baa , < dff481e12b3f127739f6a4ea7cef2c25dc12e056 (git)
Affected: 9330986c03006ab1d33d243b7cfe598a7a3c1baa , < 11c1e836710dcba03e50454a4eedfdbaf8d3050e (git)
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Linux Linux Affected: 5.16
Unaffected: 0 , < 5.16 (semver)
Unaffected: 6.1.188 , ≤ 6.1.* (semver)
Unaffected: 6.6.157 , ≤ 6.6.* (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
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      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Harden bloom filter sizing and indexing on 32-bit kernels\n\nbloom_map_alloc() has two 32-bit-specific problems when the computed\nbitmap reaches the U32_MAX fallback case.\n\nFirst, BITS_TO_BYTES(U32_MAX) is evaluated with 32-bit arithmetic. The\naddition performed by DIV_ROUND_UP wraps, so the map allocates only the\nfixed-size bloom filter object while keeping bitset_mask == U32_MAX.\nSubsequent updates can then write past the allocated object.\n\nSecond, fixing only the allocation size is not sufficient. The bloom hash\nis a u32, but set_bit() takes a signed long bit number and x86 test_bit()\neventually feeds the index to variable_test_bit(long, ...). On 32-bit\nkernels, hashes in [0x80000000, U32_MAX] therefore become negative bit\noffsets. x86 bt/bts with a memory operand interpret those offsets relative\nto the supplied base, so a map with bitset_mask == U32_MAX can read or\nwrite before bloom-\u003ebitset even after allocating the full 512 MiB bitmap.\n\nKeep the U32_MAX fallback, but split each hash into a word pointer and an\nin-word bit number before calling test_bit() or set_bit(). The bitops\nargument is then always in [0, BITS_PER_LONG - 1], while BIT_WORD(h) still\nselects the intended word in the full bitmap.\n\nCompute the bitset size from (u64)bitset_mask + 1 before passing the final\nsize to bpf_map_area_alloc(). This fixes the original under-allocation and\nkeeps the allocated storage consistent with the addressable bitset.\n\nExploitation note: local privilege escalation is possible on a 32-bit x86\nkernel using the under-allocation bug from a binary with CAP_BPF."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
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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",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is reached only via local bpf(2) syscalls: BPF_MAP_CREATE of BPF_MAP_TYPE_BLOOM_FILTER, then BPF_MAP_UPDATE_ELEM/LOOKUP_ELEM which call bloom_map_push_elem/peek_elem. Per kernel CNA guidance BPF is Local, not network-reachable.\nAC:L - On a 32-bit kernel the attacker deterministically forces the U32_MAX bitmap fallback with a large max_entries so BITS_TO_BYTES wraps and under-allocates; BPF_F_ZERO_SEED and chosen values then drive set_bit/test_bit to selected out-of-bounds indexes with no race or uncontrolled layout.\nPR:L - Creating a bloom-filter map requires CAP_BPF in map_create_alloc (bpf_token_capable). Per kernel guidance this is Low because CAP_BPF is obtainable via user namespaces and BPF token delegation, not only init-namespace root.\nUI:N - The attacker creates the undersized bloom map and issues lookup/update syscalls from their own process; no victim action such as mounting a filesystem or opening a file is required.\nS:U - The out-of-bounds bit set/test corrupts kernel heap around the undersized bloom object on the same host. This is standard kernel memory corruption and privilege escalation, not a VM escape or IOMMU boundary bypass.\nC:H - With bitset_mask==U32_MAX and a near-empty allocation, bloom_map_peek_elem\u0027s test_bit is an out-of-bounds kernel bit-read oracle, and the matching OOB writes enable heap disclosure; kernel guidance rates such memory corruption as High confidentiality impact.\nI:H - bloom_map_push_elem\u0027s set_bit writes past (and on 32-bit x86, before) the allocated object across a huge range, a controllable OOB write. The fix commit documents local privilege escalation from CAP_BPF on 32-bit x86.\nA:H - The same unbounded set_bit/test_bit indexes unmapped pages around the undersized kmalloc object and reliably produces a kernel oops or panic, which is High availability impact per kernel guidance."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-14T12:01:09.673Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/11c1e836710dcba03e50454a4eedfdbaf8d3050e"
        }
      ],
      "title": "bpf: Harden bloom filter sizing and indexing on 32-bit kernels",
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89579",
    "datePublished": "2026-09-11T19:44:46.110Z",
    "dateReserved": "2026-09-11T19:38:34.728Z",
    "dateUpdated": "2026-09-14T12:01:09.673Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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      "date": "2026-09-16",
      "epss": "0.00167",
      "percentile": "0.06351"
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The bloom hash\\nis a u32, but set_bit() takes a signed long bit number and x86 test_bit()\\neventually feeds the index to variable_test_bit(long, ...). On 32-bit\\nkernels, hashes in [0x80000000, U32_MAX] therefore become negative bit\\noffsets. x86 bt/bts with a memory operand interpret those offsets relative\\nto the supplied base, so a map with bitset_mask == U32_MAX can read or\\nwrite before bloom-\u003ebitset even after allocating the full 512 MiB bitmap.\\n\\nKeep the U32_MAX fallback, but split each hash into a word pointer and an\\nin-word bit number before calling test_bit() or set_bit(). The bitops\\nargument is then always in [0, BITS_PER_LONG - 1], while BIT_WORD(h) still\\nselects the intended word in the full bitmap.\\n\\nCompute the bitset size from (u64)bitset_mask + 1 before passing the final\\nsize to bpf_map_area_alloc(). This fixes the original under-allocation and\\nkeeps the allocated storage consistent with the addressable bitset.\\n\\nExploitation note: local privilege escalation is possible on a 32-bit x86\\nkernel using the under-allocation bug from a binary with CAP_BPF.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"kernel/bpf/bloom_filter.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\"lessThan\":\"a6183bc683f97f4317f7e84939ca7fff37c5688b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\"lessThan\":\"80551bf8912c42d1e3d55eec6fa3c40f306c3de8\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\"lessThan\":\"3b7a13eccfcf97714ffc1ca6aa663d66d4a30e29\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\"lessThan\":\"272fcb4ba6fab678db0eb966dc81c4c804bef64a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\"lessThan\":\"dff481e12b3f127739f6a4ea7cef2c25dc12e056\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\"lessThan\":\"11c1e836710dcba03e50454a4eedfdbaf8d3050e\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"kernel/bpf/bloom_filter.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.16\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.16\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.188\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.157\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.109\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.50\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.4\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/11c1e836710dcba03e50454a4eedfdbaf8d3050e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/272fcb4ba6fab678db0eb966dc81c4c804bef64a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3b7a13eccfcf97714ffc1ca6aa663d66d4a30e29\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/80551bf8912c42d1e3d55eec6fa3c40f306c3de8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a6183bc683f97f4317f7e84939ca7fff37c5688b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/dff481e12b3f127739f6a4ea7cef2c25dc12e056\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-15T14:05:35+00:00",
      "cve": "CVE-2026-89579",
      "id": "CVE-2026-89579",
      "initial_release_date": "2026-09-11T00:00:00+00:00",
      "product_status:known_affected": "185",
      "product_status:known_not_affected": "91",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: Harden bloom filter sizing and indexing on 32-bit kernels",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89579.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-15T00:58:12Z",
      "cve": "CVE-2026-89579",
      "id": "CVE-2026-89579",
      "initial_release_date": "2026-09-15T00:58:12Z",
      "product_status:known_affected": "82",
      "product_status:known_not_affected": "271",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89579",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89579.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.

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  • 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.


Detection rules are retrieved from Rulezet.


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