{"id":"CVE-2026-93127","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Drop scalar id on sign-extending narrowing stack fills\n\nWhen a spilled scalar is filled back with a sign-extending narrowing load\n(BPF_MEMSX), check_stack_read_fix…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Drop scalar id on sign-extending narrowing stack fills\n\nWhen a spilled scalar is filled back with a sign-extending narrowing load\n(BPF_MEMSX), check_stack_read_fix…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","vendor":"Linux","product":"Linux","affected":["Linux >= 3cd5c890652ba1f0682adc291b5446245259b692 < f3614622dc41f3dd99bb4f691da253814e4e6cae","Linux >= 3cd5c890652ba1f0682adc291b5446245259b692 < 2cb5f4ca695ebe552647e5ba4aad6934d6a43bae","Linux 7.0"],"published":"2026-09-17","updated":"2026-09-18","sourceUpdated":"2026-09-18T18:18:22.070","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-93127","references":[{"url":"https://git.kernel.org/stable/c/2cb5f4ca695ebe552647e5ba4aad6934d6a43bae","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f3614622dc41f3dd99bb4f691da253814e4e6cae","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"epss":0.00165,"epssPercentile":0.05028,"ingestedAt":"2026-09-17T16:21:47.749Z","slug":"CVE-2026-93127","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Drop scalar id on sign-extending narrowing stack fills\n\nWhen a spilled scalar is filled back with a sign-extending narrowing load\n(BPF_MEMSX), check_stack_read_fixed_off() copies the spilled register\nincluding its scalar id, but coerce_reg_to_size_sx() then sign-extends the\nfilled register's value. If the same slot is also filled with a plain\nzero-extending load (BPF_MEM), both destination registers share the id yet\nhold different values. A later 'if <zext-reg> == const' then refines the\nsign-extended register through sync_linked_regs() to a value it does not\nhave at runtime (e.g. the verifier believes 0x80000000 while the register\nis 0xffffffff80000000), which can be turned into an out-of-bounds access.\n\nDrop the shared scalar id at the sign-extension site in check_mem_access()\nwhen sign extension actually changes the value, mirroring the BPF_MOVSX\nhandling in check_alu_op() (no_sext = reg_umax < 2^(size*8-1)).\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":207387,"id":"CVE-2026-93127","ts":1789757342788,"field":"cvss","old":null,"new":"7.8"},{"seq":207386,"id":"CVE-2026-93127","ts":1789757342788,"field":"severity","old":"none","new":"high"}]}