{"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":"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-681"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 6.10, < 7.2.7","linux_kernel = 7.3"],"patched":["linux_kernel 7.2.7"],"published":"2026-09-25","updated":"2026-10-15","sourceUpdated":"2026-10-15T11:18:10.553","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"},{"url":"https://git.kernel.org/stable/c/6bb6ae5ab1beffda51dabf41612f501d07f10fc6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98049.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-98049"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2541265"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98049"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98049"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98049.mbox"},{"url":"https://git.kernel.org/stable/c/1bb1be18263995b159cf5afad3a05500ba6d2a7b"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00155,"epssPercentile":0.04559,"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## Affected\n\n- `linux_kernel >= 6.10, < 7.2.7`\n- `linux_kernel = 7.3`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.2.7`\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-28 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98049.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":212400,"id":"CVE-2026-98049","ts":1790668181794,"field":"cvss","old":null,"new":"5.5"},{"seq":212399,"id":"CVE-2026-98049","ts":1790668181794,"field":"severity","old":"none","new":"medium"}]}