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GHSA-MHP6-WW8C-XW4F

Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-09-25 12:31

Details

In the Linux kernel, the following vulnerability has been resolved:

bpf: Reject key-less BTF for hash maps

map_check_btf() allows a key-less BTF (btf_key_type_id == 0) only for maps that have a ->map_check_btf callback, and leaves the actual decision to that callback. Hash maps used to have no ->map_check_btf, so a key-less BTF was rejected outright.

That changed when htab and rhtab gained a ->map_check_btf to register a dtor - htab in commit 1df97a7453ee ("bpf: Register dtor for freeing special fields") and rhtab in commit 6905f8601298 ("bpf: Allow special fields in resizable hashtab"). Neither looks at the key, so a key-less hash map now passes map_check_btf() and gets created. Reading it back through bpffs feeds the key type_id 0 into btf_type_seq_show(); btf_type_by_id() returns the void type, kind_ops[BTF_KIND_UNKN] is NULL, and btf_type_show() dereferences it:

RIP: 0010:btf_type_show+0x223/0x2e0 kernel/bpf/btf.c:8232 RSP: 0018:ffffc9000399f868 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000028 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: ffffc9000399f970 R11: 0000000000000001 R12: ffffffff9b96b140 R13: ffffc9000399f8e0 R14: ffff88803d393c00 R15: 0000000000000003 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000000 CR3: 000000003d213000 CR4: 0000000000352ef0 DR0: 0000000039ae8f55 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: btf_type_seq_show_flags+0xca/0x120 kernel/bpf/btf.c:8250 htab_map_seq_show_elem+0x12e/0x350 kernel/bpf/hashtab.c:1669 map_seq_show+0x13d/0x1e0 kernel/bpf/inode.c:293 traverse.part.0.constprop.0+0x107/0x650 fs/seq_file.c:112 traverse fs/seq_file.c:99 [inline] seq_read_iter+0x93f/0x1270 fs/seq_file.c:196 seq_read+0x344/0x4d0 fs/seq_file.c:163 vfs_read+0x1e4/0xb40 fs/read_write.c:572 ksys_pread64 fs/read_write.c:764 [inline] __do_sys_pread64 fs/read_write.c:772 [inline] __se_sys_pread64 fs/read_write.c:769 [inline] __x64_sys_pread64+0x1eb/0x250 fs/read_write.c:769 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reject a key-less BTF in htab_map_check_btf() and rhtab_map_check_btf(), restoring the previous behavior.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98065"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-25T11:17:35Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject key-less BTF for hash maps\n\nmap_check_btf() allows a key-less BTF (btf_key_type_id == 0) only for\nmaps that have a -\u003emap_check_btf callback, and leaves the actual\ndecision to that callback. Hash maps used to have no -\u003emap_check_btf,\nso a key-less BTF was rejected outright.\n\nThat changed when htab and rhtab gained a -\u003emap_check_btf to register a\ndtor - htab in commit 1df97a7453ee (\"bpf: Register dtor for freeing\nspecial fields\") and rhtab in commit 6905f8601298 (\"bpf: Allow special\nfields in resizable hashtab\"). Neither looks at the key, so a key-less\nhash map now passes map_check_btf() and gets created. Reading it back\nthrough bpffs feeds the key type_id 0 into btf_type_seq_show();\nbtf_type_by_id() returns the void type, kind_ops[BTF_KIND_UNKN] is NULL,\nand btf_type_show() dereferences it:\n\nRIP: 0010:btf_type_show+0x223/0x2e0 kernel/bpf/btf.c:8232\nRSP: 0018:ffffc9000399f868 EFLAGS: 00010206\nRAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000\nRDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000028\nRBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000\nR10: ffffc9000399f970 R11: 0000000000000001 R12: ffffffff9b96b140\nR13: ffffc9000399f8e0 R14: ffff88803d393c00 R15: 0000000000000003\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000200000000000 CR3: 000000003d213000 CR4: 0000000000352ef0\nDR0: 0000000039ae8f55 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400\nCall Trace:\n \u003cTASK\u003e\n btf_type_seq_show_flags+0xca/0x120 kernel/bpf/btf.c:8250\n htab_map_seq_show_elem+0x12e/0x350 kernel/bpf/hashtab.c:1669\n map_seq_show+0x13d/0x1e0 kernel/bpf/inode.c:293\n traverse.part.0.constprop.0+0x107/0x650 fs/seq_file.c:112\n traverse fs/seq_file.c:99 [inline]\n seq_read_iter+0x93f/0x1270 fs/seq_file.c:196\n seq_read+0x344/0x4d0 fs/seq_file.c:163\n vfs_read+0x1e4/0xb40 fs/read_write.c:572\n ksys_pread64 fs/read_write.c:764 [inline]\n __do_sys_pread64 fs/read_write.c:772 [inline]\n __se_sys_pread64 fs/read_write.c:769 [inline]\n __x64_sys_pread64+0x1eb/0x250 fs/read_write.c:769\n do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]\n do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nReject a key-less BTF in htab_map_check_btf() and rhtab_map_check_btf(),\nrestoring the previous behavior.",
  "id": "GHSA-mhp6-ww8c-xw4f",
  "modified": "2026-09-25T12:31:35Z",
  "published": "2026-09-25T12:31:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98065"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0895a0c0734703be5532f3883c42db95615fd98b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7ca231252820c47aaec42a5db580db98f9b64724"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-98065 (GCVE-0-2026-98065)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:24 – Updated: 2026-09-25 10:24

Title

bpf: Reject key-less BTF for hash maps

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject key-less BTF for hash maps map_check_btf() allows a key-less BTF (btf_key_type_id == 0) only for maps that have a ->map_check_btf callback, and leaves the actual decision to that callback. Hash maps used to have no ->map_check_btf, so a key-less BTF was rejected outright. That changed when htab and rhtab gained a ->map_check_btf to register a dtor - htab in commit 1df97a7453ee ("bpf: Register dtor for freeing special fields") and rhtab in commit 6905f8601298 ("bpf: Allow special fields in resizable hashtab"). Neither looks at the key, so a key-less hash map now passes map_check_btf() and gets created. Reading it back through bpffs feeds the key type_id 0 into btf_type_seq_show(); btf_type_by_id() returns the void type, kind_ops[BTF_KIND_UNKN] is NULL, and btf_type_show() dereferences it: RIP: 0010:btf_type_show+0x223/0x2e0 kernel/bpf/btf.c:8232 RSP: 0018:ffffc9000399f868 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000028 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: ffffc9000399f970 R11: 0000000000000001 R12: ffffffff9b96b140 R13: ffffc9000399f8e0 R14: ffff88803d393c00 R15: 0000000000000003 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000000 CR3: 000000003d213000 CR4: 0000000000352ef0 DR0: 0000000039ae8f55 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: <TASK> btf_type_seq_show_flags+0xca/0x120 kernel/bpf/btf.c:8250 htab_map_seq_show_elem+0x12e/0x350 kernel/bpf/hashtab.c:1669 map_seq_show+0x13d/0x1e0 kernel/bpf/inode.c:293 traverse.part.0.constprop.0+0x107/0x650 fs/seq_file.c:112 traverse fs/seq_file.c:99 [inline] seq_read_iter+0x93f/0x1270 fs/seq_file.c:196 seq_read+0x344/0x4d0 fs/seq_file.c:163 vfs_read+0x1e4/0xb40 fs/read_write.c:572 ksys_pread64 fs/read_write.c:764 [inline] __do_sys_pread64 fs/read_write.c:772 [inline] __se_sys_pread64 fs/read_write.c:769 [inline] __x64_sys_pread64+0x1eb/0x250 fs/read_write.c:769 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f Reject a key-less BTF in htab_map_check_btf() and rhtab_map_check_btf(), restoring the previous behavior.

Severity

No CVSS data available.

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/7ca231252820c47aa…
https://git.kernel.org/stable/c/0895a0c0734703be5…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 1df97a7453eec80c1912c2d0360290a3970a7671 , < 7ca231252820c47aaec42a5db580db98f9b64724 (git) Affected: 1df97a7453eec80c1912c2d0360290a3970a7671 , < 0895a0c0734703be5532f3883c42db95615fd98b (git)
Linux	Linux	Affected: 7.0 Unaffected: 0 , < 7.0 (semver) Unaffected: 7.2.7 , ≤ 7.2.* (semver) Unaffected: 7.3-rc2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/hashtab.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "7ca231252820c47aaec42a5db580db98f9b64724",
              "status": "affected",
              "version": "1df97a7453eec80c1912c2d0360290a3970a7671",
              "versionType": "git"
            },
            {
              "lessThan": "0895a0c0734703be5532f3883c42db95615fd98b",
              "status": "affected",
              "version": "1df97a7453eec80c1912c2d0360290a3970a7671",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/hashtab.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.7",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc2",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject key-less BTF for hash maps\n\nmap_check_btf() allows a key-less BTF (btf_key_type_id == 0) only for\nmaps that have a -\u003emap_check_btf callback, and leaves the actual\ndecision to that callback. Hash maps used to have no -\u003emap_check_btf,\nso a key-less BTF was rejected outright.\n\nThat changed when htab and rhtab gained a -\u003emap_check_btf to register a\ndtor - htab in commit 1df97a7453ee (\"bpf: Register dtor for freeing\nspecial fields\") and rhtab in commit 6905f8601298 (\"bpf: Allow special\nfields in resizable hashtab\"). Neither looks at the key, so a key-less\nhash map now passes map_check_btf() and gets created. Reading it back\nthrough bpffs feeds the key type_id 0 into btf_type_seq_show();\nbtf_type_by_id() returns the void type, kind_ops[BTF_KIND_UNKN] is NULL,\nand btf_type_show() dereferences it:\n\nRIP: 0010:btf_type_show+0x223/0x2e0 kernel/bpf/btf.c:8232\nRSP: 0018:ffffc9000399f868 EFLAGS: 00010206\nRAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000\nRDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000028\nRBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000\nR10: ffffc9000399f970 R11: 0000000000000001 R12: ffffffff9b96b140\nR13: ffffc9000399f8e0 R14: ffff88803d393c00 R15: 0000000000000003\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000200000000000 CR3: 000000003d213000 CR4: 0000000000352ef0\nDR0: 0000000039ae8f55 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400\nCall Trace:\n \u003cTASK\u003e\n btf_type_seq_show_flags+0xca/0x120 kernel/bpf/btf.c:8250\n htab_map_seq_show_elem+0x12e/0x350 kernel/bpf/hashtab.c:1669\n map_seq_show+0x13d/0x1e0 kernel/bpf/inode.c:293\n traverse.part.0.constprop.0+0x107/0x650 fs/seq_file.c:112\n traverse fs/seq_file.c:99 [inline]\n seq_read_iter+0x93f/0x1270 fs/seq_file.c:196\n seq_read+0x344/0x4d0 fs/seq_file.c:163\n vfs_read+0x1e4/0xb40 fs/read_write.c:572\n ksys_pread64 fs/read_write.c:764 [inline]\n __do_sys_pread64 fs/read_write.c:772 [inline]\n __se_sys_pread64 fs/read_write.c:769 [inline]\n __x64_sys_pread64+0x1eb/0x250 fs/read_write.c:769\n do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]\n do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nReject a key-less BTF in htab_map_check_btf() and rhtab_map_check_btf(),\nrestoring the previous behavior."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T10:24:08.406Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/7ca231252820c47aaec42a5db580db98f9b64724"
        },
        {
          "url": "https://git.kernel.org/stable/c/0895a0c0734703be5532f3883c42db95615fd98b"
        }
      ],
      "title": "bpf: Reject key-less BTF for hash maps",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98065",
    "datePublished": "2026-09-25T10:24:08.406Z",
    "dateReserved": "2026-09-25T10:19:56.073Z",
    "dateUpdated": "2026-09-25T10:24:08.406Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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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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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.

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GHSA-MHP6-WW8C-XW4F

CVE-2026-98065 (GCVE-0-2026-98065)

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