{"id":"CVE-2026-98065","title":"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 ->map_check_btf callback, and leaves the …","summary":"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 ->map_check_btf callback, and leaves the …","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-476"],"vendor":"Linux","product":"Linux","affected":["Linux >= 451a84a3ad3c897c03181af433e7c98640730f1f < 54098e3fe34ec190bc256b338b9a93c7e2dc9354","Linux >= 51a17f0ce19c4ee2a25cf16c93490d509b1ebb0a < fa047f2a025003f5654ebd76539f16a6ead0401a","Linux >= 1df97a7453eec80c1912c2d0360290a3970a7671 < 7ca231252820c47aaec42a5db580db98f9b64724","Linux >= 1df97a7453eec80c1912c2d0360290a3970a7671 < 0895a0c0734703be5532f3883c42db95615fd98b","Linux 7.0"],"published":"2026-09-25","updated":"2026-10-03","sourceUpdated":"2026-10-03T11:18:27.217","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-98065","references":[{"url":"https://git.kernel.org/stable/c/0895a0c0734703be5532f3883c42db95615fd98b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/54098e3fe34ec190bc256b338b9a93c7e2dc9354","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7ca231252820c47aaec42a5db580db98f9b64724","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fa047f2a025003f5654ebd76539f16a6ead0401a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98065.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-98065"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2541294"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98065"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98065"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98065.mbox"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00168,"epssPercentile":0.05985,"cvssSource":"vendor","ingestedAt":"2026-09-25T11:06:38.842Z","slug":"CVE-2026-98065","body":"## Overview\n\nIn 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 ->map_check_btf callback, and leaves the actual\ndecision to that callback. Hash maps used to have no ->map_check_btf,\nso a key-less BTF was rejected outright.\n\nThat changed when htab and rhtab gained a ->map_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 <TASK>\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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-29 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98065.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":212369,"id":"CVE-2026-98065","ts":1790668159264,"field":"cvss","old":null,"new":"5.5"},{"seq":212368,"id":"CVE-2026-98065","ts":1790668159264,"field":"severity","old":"none","new":"medium"}]}