CVE-2026-98378 (GCVE-0-2026-98378)

Vulnerability from cvelistv5 – Published: 2026-10-09 07:34 – Updated: 2026-10-24 14:08
VLAI
Title
bpf: Skip unsettled links in link iterator
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Skip unsettled links in link iterator bpf_link_prime() inserts a link into link_idr before anon_inode_getfile() succeeds and before bpf_link_settle() publishes the ID in link->id. bpf_link_by_id() treats such an ID-zero link as unsettled, but the link iterator takes a reference without this check. If anon_inode_getfile() then fails, the creator removes the ID and frees its still-private link directly. The iterator is left with a dangling reference and its next bpf_link_put() accesses freed memory. Treat ID-zero entries as transient in bpf_link_get_curr_or_next(), just as bpf_link_by_id() does. BUG: KASAN: slab-use-after-free in bpf_link_put Write of size 8 by task exp/384 Call Trace: bpf_link_put kernel/bpf/syscall.c:3372 bpf_link_seq_next kernel/bpf/link_iter.c:33 bpf_seq_read kernel/bpf/bpf_iter.c:158 vfs_read fs/read_write.c:572 ksys_read fs/read_write.c:716 do_syscall_64 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe arch/x86/entry/entry_64.S:121 Kernel panic - not syncing: KASAN: panic_on_warn set ...
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7018 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 9f88361273082825d9f0d13a543d49f9fa0d44a8 , < 68930f8d40ab4c10ca3b019f076136758fd100a8 (git)
Affected: 9f88361273082825d9f0d13a543d49f9fa0d44a8 , < c251ed48bd9063cf7de6049421e78b6de989060f (git)
Affected: 9f88361273082825d9f0d13a543d49f9fa0d44a8 , < 798a61edbc436cacdb659927d067368eeb1e30e2 (git)
Affected: 9f88361273082825d9f0d13a543d49f9fa0d44a8 , < 6e271f093d15d323f42de26f66556af53fa8e19f (git)
Affected: 9f88361273082825d9f0d13a543d49f9fa0d44a8 , < 87ce4b53b7436b50fc984f0a6afaf77f68ac5573 (git)
Affected: 9f88361273082825d9f0d13a543d49f9fa0d44a8 , < 50e80e2bb5e2be8515205b9c496b9640ddefa434 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.19
Unaffected: 0 , < 5.19 (semver)
Unaffected: 6.1.189 , ≤ 6.1.* (semver)
Unaffected: 6.6.158 , ≤ 6.6.* (semver)
Unaffected: 6.12.112 , ≤ 6.12.* (semver)
Unaffected: 6.18.55 , ≤ 6.18.* (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
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          "programFiles": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Skip unsettled links in link iterator\n\nbpf_link_prime() inserts a link into link_idr before anon_inode_getfile()\nsucceeds and before bpf_link_settle() publishes the ID in link-\u003eid.\nbpf_link_by_id() treats such an ID-zero link as unsettled, but the link\niterator takes a reference without this check.\n\nIf anon_inode_getfile() then fails, the creator removes the ID and frees\nits still-private link directly.  The iterator is left with a dangling\nreference and its next bpf_link_put() accesses freed memory.\n\nTreat ID-zero entries as transient in bpf_link_get_curr_or_next(), just as\nbpf_link_by_id() does.\n\n  BUG: KASAN: slab-use-after-free in bpf_link_put\n  Write of size 8 by task exp/384\n  Call Trace:\n  bpf_link_put                    kernel/bpf/syscall.c:3372\n  bpf_link_seq_next               kernel/bpf/link_iter.c:33\n  bpf_seq_read                    kernel/bpf/bpf_iter.c:158\n  vfs_read                        fs/read_write.c:572\n  ksys_read                       fs/read_write.c:716\n  do_syscall_64                   arch/x86/entry/syscall_64.c:84\n  entry_SYSCALL_64_after_hwframe  arch/x86/entry/entry_64.S:121\n  Kernel panic - not syncing: KASAN: panic_on_warn set ..."
        }
      ],
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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"
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              "value": "AV:L - Both required paths are local: bpf(BPF_LINK_CREATE/BPF_ITER_CREATE) prepares the bpf_link iterator, and read() reaches bpf_seq_read() -\u003e bpf_link_seq_next() -\u003e the patched bpf_link_get_curr_or_next(); no network data enters this state.\nAC:L - The attacker can fill fs.file-max so anon_inode_getfile() returns -ENFILE, then run the iterator reader and repeated BPF_LINK_CREATE calls concurrently, controlling both sides of the IDR insert/remove race.\nPR:L - BPF_PROG_LOAD for BPF_PROG_TYPE_TRACING/BPF_TRACE_ITER requires CAP_BPF and CAP_PERFMON, but bpf_token_capable() accepts them in a delegated bpffs token\u0027s user namespace; this permits a namespace-root local user, while a bare user namespace does not.\nUI:N - After preparing the iterator and program FDs, the attacking process itself issues read() and concurrent BPF_LINK_CREATE calls; no victim action is required.\nS:U - bpf_link_get_curr_or_next() leaves a dangling object inside the same host kernel that services the BPF syscalls; it crosses no guest/host, IOMMU, or separate security authority boundary.\nC:H - The iterator retains a freed struct bpf_link pointer; reclaiming that slab object makes later bpf_link_put()/bpf_link_free() consume attacker-influenced refcnt, ops, and prog fields, supporting kernel-memory disclosure.\nI:H - bpf_link_put() performs atomic64_dec_and_test() on the freed object\u0027s first eight bytes and can initialize and queue its reclaimed work_struct, so controlled reuse supports arbitrary corruption or control-flow hijacking.\nA:H - The demonstrated read() path reaches bpf_link_seq_next() and bpf_link_put() after the link is freed, producing a KASAN use-after-free and kernel panic; the same stale write can crash a non-KASAN kernel."
            }
          ]
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      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:08:37.091Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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      ],
      "title": "bpf: Skip unsettled links in link iterator",
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98378",
    "datePublished": "2026-10-09T07:34:18.626Z",
    "dateReserved": "2026-09-25T10:25:14.345Z",
    "dateUpdated": "2026-10-24T14:08:37.091Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
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      "date": "2026-11-01",
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      "id": "msrc_CVE-2026-98378",
      "initial_release_date": "2026-10-10T01:11:06.000Z",
      "product_status:fixed": "1",
      "product_status:known_affected": "1",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "bpf: Skip unsettled links in link iterator",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98378.json",
      "version": "4"
    },
    "nvd": {
      "cve": {
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        "cveTags": [],
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          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Skip unsettled links in link iterator\n\nbpf_link_prime() inserts a link into link_idr before anon_inode_getfile()\nsucceeds and before bpf_link_settle() publishes the ID in link-\u003eid.\nbpf_link_by_id() treats such an ID-zero link as unsettled, but the link\niterator takes a reference without this check.\n\nIf anon_inode_getfile() then fails, the creator removes the ID and frees\nits still-private link directly.  The iterator is left with a dangling\nreference and its next bpf_link_put() accesses freed memory.\n\nTreat ID-zero entries as transient in bpf_link_get_curr_or_next(), just as\nbpf_link_by_id() does.\n\n  BUG: KASAN: slab-use-after-free in bpf_link_put\n  Write of size 8 by task exp/384\n  Call Trace:\n  bpf_link_put                    kernel/bpf/syscall.c:3372\n  bpf_link_seq_next               kernel/bpf/link_iter.c:33\n  bpf_seq_read                    kernel/bpf/bpf_iter.c:158\n  vfs_read                        fs/read_write.c:572\n  ksys_read                       fs/read_write.c:716\n  do_syscall_64                   arch/x86/entry/syscall_64.c:84\n  entry_SYSCALL_64_after_hwframe  arch/x86/entry/entry_64.S:121\n  Kernel panic - not syncing: KASAN: panic_on_warn set ..."
          }
        ],
        "id": "CVE-2026-98378",
        "lastModified": "2026-10-24T14:16:39.873",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "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",
                "version": "3.1"
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              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-10-09T08:16:56.123",
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            "url": "https://git.kernel.org/stable/c/c251ed48bd9063cf7de6049421e78b6de989060f"
          }
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-10-30T04:35:28+00:00",
      "cve": "CVE-2026-98378",
      "id": "CVE-2026-98378",
      "initial_release_date": "2026-10-09T00:00:00+00:00",
      "product_status:known_affected": "188",
      "product_status:known_not_affected": "91",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: Skip unsettled links in link iterator",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98378.json",
      "version": "3"
    }
  }
}



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    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.