{"api_version":"1","generated_at":"2026-10-04T11:44:17+00:00","cve":"CVE-2026-98049","urls":{"html":"https://cve.report/CVE-2026-98049","api":"https://cve.report/api/cve/CVE-2026-98049.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98049","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98049"},"summary":{"title":"bpf: zero extend the result of an arena 32-bit cmpxchg","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: zero extend the result of an arena 32-bit cmpxchg\n\nbpf_convert_ctx_accesses() rewrites an atomic on an arena pointer from\nBPF_STX | BPF_ATOMIC to BPF_STX | BPF_PROBE_ATOMIC, and it runs before\nbpf_opt_subreg_zext_lo32_rnd_hi32().\n\nThat pass emits an explicit zero extension for a 32-bit cmpxchg even\nwhen bpf_jit_needs_zext() is false. This is done because on some\narchitectures 32-bit cmpxchg requires explicit zero extension for the\ndst register. E.g. on x86-64 'lock cmpxchg' does not change the %eax\nif comparison is successful, while BPF semantics declare that each\noperation on a 32-bit register zero extends it's upper half.\n\nis_cmpxchg_insn() matches BPF_MODE == BPF_ATOMIC only, so an arena\ncmpxchg misses said zero extension adjustment. This patch adjusts\nis_cmpxchg_insn() to match BPF_PROBE_ATOMIC alongside BPF_ATOMIC.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-25 11:17:33","updated_at":"2026-09-30 14:10:59"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/1c1b476d43a8b6c9bc04600369dd8cc39950d98e","name":"https://git.kernel.org/stable/c/1c1b476d43a8b6c9bc04600369dd8cc39950d98e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4814ed6406f3493bd554ad046da5f7fc04833571","name":"https://git.kernel.org/stable/c/4814ed6406f3493bd554ad046da5f7fc04833571","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98049","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98049","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d503a04f8bc0c75dc9db9452d8cc79d748afb752 1c1b476d43a8b6c9bc04600369dd8cc39950d98e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d503a04f8bc0c75dc9db9452d8cc79d748afb752 4814ed6406f3493bd554ad046da5f7fc04833571 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.10","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.10 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.7 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"98049","cve":"CVE-2026-98049","epss":"0.001550000","percentile":"0.039790000","score_date":"2026-09-27","updated_at":"2026-09-28 00:02:24"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["kernel/bpf/fixups.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"1c1b476d43a8b6c9bc04600369dd8cc39950d98e","status":"affected","version":"d503a04f8bc0c75dc9db9452d8cc79d748afb752","versionType":"git"},{"lessThan":"4814ed6406f3493bd554ad046da5f7fc04833571","status":"affected","version":"d503a04f8bc0c75dc9db9452d8cc79d748afb752","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["kernel/bpf/fixups.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.10"},{"lessThan":"6.10","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":"6.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc2","versionStartIncluding":"6.10","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: zero extend the result of an arena 32-bit cmpxchg\n\nbpf_convert_ctx_accesses() rewrites an atomic on an arena pointer from\nBPF_STX | BPF_ATOMIC to BPF_STX | BPF_PROBE_ATOMIC, and it runs before\nbpf_opt_subreg_zext_lo32_rnd_hi32().\n\nThat pass emits an explicit zero extension for a 32-bit cmpxchg even\nwhen bpf_jit_needs_zext() is false. This is done because on some\narchitectures 32-bit cmpxchg requires explicit zero extension for the\ndst register. E.g. on x86-64 'lock cmpxchg' does not change the %eax\nif comparison is successful, while BPF semantics declare that each\noperation on a 32-bit register zero extends it's upper half.\n\nis_cmpxchg_insn() matches BPF_MODE == BPF_ATOMIC only, so an arena\ncmpxchg misses said zero extension adjustment. This patch adjusts\nis_cmpxchg_insn() to match BPF_PROBE_ATOMIC alongside BPF_ATOMIC."}],"providerMetadata":{"dateUpdated":"2026-09-25T10:23:58.561Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/1c1b476d43a8b6c9bc04600369dd8cc39950d98e"},{"url":"https://git.kernel.org/stable/c/4814ed6406f3493bd554ad046da5f7fc04833571"}],"title":"bpf: zero extend the result of an arena 32-bit cmpxchg","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98049","datePublished":"2026-09-25T10:23:58.561Z","dateReserved":"2026-09-25T10:19:56.072Z","dateUpdated":"2026-09-25T10:23:58.561Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-25 11:17:33","lastModifiedDate":"2026-09-30 14:10:59","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98049","Ordinal":"1","Title":"bpf: zero extend the result of an arena 32-bit cmpxchg","CVE":"CVE-2026-98049","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98049","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: zero extend the result of an arena 32-bit cmpxchg\n\nbpf_convert_ctx_accesses() rewrites an atomic on an arena pointer from\nBPF_STX | BPF_ATOMIC to BPF_STX | BPF_PROBE_ATOMIC, and it runs before\nbpf_opt_subreg_zext_lo32_rnd_hi32().\n\nThat pass emits an explicit zero extension for a 32-bit cmpxchg even\nwhen bpf_jit_needs_zext() is false. This is done because on some\narchitectures 32-bit cmpxchg requires explicit zero extension for the\ndst register. E.g. on x86-64 'lock cmpxchg' does not change the %eax\nif comparison is successful, while BPF semantics declare that each\noperation on a 32-bit register zero extends it's upper half.\n\nis_cmpxchg_insn() matches BPF_MODE == BPF_ATOMIC only, so an arena\ncmpxchg misses said zero extension adjustment. This patch adjusts\nis_cmpxchg_insn() to match BPF_PROBE_ATOMIC alongside BPF_ATOMIC.","Type":"Description","Title":"bpf: zero extend the result of an arena 32-bit cmpxchg"}]}}}