{"id":"CVE-2026-98049","title":"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_PRO…","summary":"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_PRO…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= d503a04f8bc0c75dc9db9452d8cc79d748afb752 < 1c1b476d43a8b6c9bc04600369dd8cc39950d98e","Linux >= d503a04f8bc0c75dc9db9452d8cc79d748afb752 < 4814ed6406f3493bd554ad046da5f7fc04833571","Linux 6.10"],"published":"2026-09-25","updated":"2026-09-25","sourceUpdated":"2026-09-25T11:17:33.770","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-98049","references":[{"url":"https://git.kernel.org/stable/c/1c1b476d43a8b6c9bc04600369dd8cc39950d98e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/4814ed6406f3493bd554ad046da5f7fc04833571","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-25T11:06:38.848Z","slug":"CVE-2026-98049","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}