CVE-2026-98378 (GCVE-0-2026-98378)
Vulnerability from cvelistv5
Published
2026-10-09 07:34
Modified
2026-10-24 14:08
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: 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 ...
References
Impacted products
Vendor Product Version
Linux Linux Version: 9f88361273082825d9f0d13a543d49f9fa0d44a8
Version: 9f88361273082825d9f0d13a543d49f9fa0d44a8
Version: 9f88361273082825d9f0d13a543d49f9fa0d44a8
Version: 9f88361273082825d9f0d13a543d49f9fa0d44a8
Version: 9f88361273082825d9f0d13a543d49f9fa0d44a8
Version: 9f88361273082825d9f0d13a543d49f9fa0d44a8
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/syscall.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "5.19"
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              "status": "unaffected",
              "version": "0",
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              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.189",
                  "versionStartIncluding": "5.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.158",
                  "versionStartIncluding": "5.19",
                  "vulnerable": true
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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: 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 ..."
        }
      ],
      "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 - 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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:08:37.091Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/68930f8d40ab4c10ca3b019f076136758fd100a8"
        },
        {
          "url": "https://git.kernel.org/stable/c/c251ed48bd9063cf7de6049421e78b6de989060f"
        },
        {
          "url": "https://git.kernel.org/stable/c/798a61edbc436cacdb659927d067368eeb1e30e2"
        },
        {
          "url": "https://git.kernel.org/stable/c/6e271f093d15d323f42de26f66556af53fa8e19f"
        },
        {
          "url": "https://git.kernel.org/stable/c/87ce4b53b7436b50fc984f0a6afaf77f68ac5573"
        },
        {
          "url": "https://git.kernel.org/stable/c/50e80e2bb5e2be8515205b9c496b9640ddefa434"
        }
      ],
      "title": "bpf: Skip unsettled links in link iterator",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "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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