# CVE-2026-98599: bpf: Reject non-negative offsets in stack_slot_obj_get_spi()

CVE-2026-98599 is fixed in linux on 1 platform by DEBIAN-CVE-2026-98599 (version 7.2.9-1), released October 19, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-98599
- Priority: Routine
- CVSS: 6.7 (Moderate)
- EPSS: 0.0019
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 18, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-98599

## Description

In the Linux kernel, the following vulnerability has been resolved:  bpf: Reject non-negative offsets in stack_slot_obj_get_spi()  bpf_get_spi() computes (-off - 1) / BPF_REG_SIZE using C division, which truncates toward zero. For off == 0, this produces spi 0, the same index used by the valid stack slot at fp-8.  stack_slot_obj_get_spi() currently checks alignment and the resulting spi bounds, but does not reject the non-negative offset itself. It can therefore validate a PTR_TO_STACK register holding fp+0 against an iterator stored at fp-8 even though the runtime receives the actual fp+0 pointer. An effectful iterator kfunc can then interpret memory outside the BPF stack as iterator state.  Reject non-negative offsets before converting the offset to an spi. All valid stack objects begin at a negative offset from the frame pointer.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.2.9-1 | [DEBIAN-CVE-2026-98599](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98599.md) | Oct 19, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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