{"id":"CVE-2026-98044","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject legacy packet loads from callbacks\n\ncheck_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a\nsubprogram as an implicit return with R0 set to zero","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject legacy packet loads from callbacks\n\ncheck_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a\nsubprogram as an implicit return with R0 set to zero. It ca…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= ce01a4e5cfac7adbe0be565f90cd32ecbb2f8337 < 3484a99303912db62428494a9061212049027e57","Linux >= ee861486e377edc55361c08dcbceab3f6b6577bd < bc489c0c9b8c86bd7fac42cfd1bb152f042fca56","Linux >= ee861486e377edc55361c08dcbceab3f6b6577bd < e7d28823c662128caae63f14e16bd394916c139b","Linux 928d354ae3557e8f755a227e67be88034eb3cd7f","Linux 8a800497d9f6c2ec9c2c1ba7b71d0ac2ea7f7bbe","Linux de1055e7f9e67af32b1f3376066272b04e5223c0","Linux 37ad2bb11e9de92cb7b94548705eeedd87f7d392","Linux 8674e2db06cff6b50f2216eed9a761d15425bb34","Linux d846d83bdacbd8f14fc45c63b8c1d22608452e1c","Linux >= 6.18.42 < 6.18.53","Linux >= 5.10.265 < 5.11","Linux >= 5.15.216 < 5.16","Linux >= 6.1.183 < 6.2","Linux >= 6.6.148 < 6.7","Linux >= 6.12.101 < 6.13","Linux >= 7.0.10 < 7.1","Linux 7.1"],"published":"2026-09-25","updated":"2026-09-25","sourceUpdated":"2026-09-25T11:17:33.200","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-98044","references":[{"url":"https://git.kernel.org/stable/c/3484a99303912db62428494a9061212049027e57","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bc489c0c9b8c86bd7fac42cfd1bb152f042fca56","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e7d28823c662128caae63f14e16bd394916c139b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-25T11:06:38.848Z","slug":"CVE-2026-98044","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject legacy packet loads from callbacks\n\ncheck_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a\nsubprogram as an implicit return with R0 set to zero. It calls\nprepare_func_exit() to explore this synthesized path.\n\nWhen the load is reached directly from a synchronous callback,\nprepare_func_exit() enforces the callback return contract and marks R0\nprecise. R0 is not derived from a real instruction on this path, so\nprecision backtracking reaches the callback call with R0 still requested\nand triggers the \"callback unexpected regs\" verifier bug. A privileged\nprogram loader can therefore cause a verifier warning and an -EFAULT\nBPF_PROG_LOAD.\n\nThese legacy packet-load instructions are deprecated. Reject them from\ncallbacks rather than complicating their implicit-return model. Check all\nactive frames before constructing the implicit return so nested static\nsubprograms cannot hide the callback context.\n\nGlobal functions are verified independently with a fresh frame zero, so\nan active-frame check cannot identify a global function called from a\ncallback. Also check the complete subprogram call graph during stack-depth\nvalidation and reject a function containing a legacy load when any caller\nis a callback. This covers global and static descendants without making\nhas_ld_abs transitive, preserving its per-function BTF return-type check.\nOrdinary uses outside callbacks remain supported.\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":[]}