---
id: "CVE-2026-98589"
kind: "vulnerability"
aliases: ["CVE-2026-98589"]
title: "Linux kernel: BPF verifier lets packet pointers reach mutating subprograms"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["bpf", "ebpf", "infrastructure", "kernel", "linux"]
not_affected_if: []
published_at: "2026-10-18T16:17:11+00:00"
first_seen_at: "2026-10-23T21:57:15+00:00"
updated_at: "2026-10-25T05:21:44+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98589", "first_seen_at": "2026-10-23T21:57:15+00:00"}]
---

# Linux kernel: BPF verifier lets packet pointers reach mutating subprograms

The BPF verifier in the Linux kernel could pass packet pointers into subprograms that may modify the packet, so a pointer can be left pointing at memory a pskb_* call has invalidated. The fix makes the verifier reject such programs unless the subprogram is guaranteed not to mutate the packet.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-10-23T21:57:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98589

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

bpf: Reject pkt arguments in mutating subprogs

The verifier tracks changes in how PTR_TO_PACKET registers'
bounds are modified across subprog boundaries. PTR_TO_PACKET
registers are actually passed as PTR_TO_MEM, which is assumed
valid for the entire call. This is not the case with packet memory,
where a pskb_* call may invalidate its memory region.

Reject BPF code that passes PTR_TO_PACKET pointers to subprogs that
may mutate a packet. We cannot pass the pointer as a true PTR_TO_PACKET
because we would also need to somehow pass the PTR_TO_PACKET_META
or PTR_TO_PACKET_END to the subprog. Since we cannot avoid representing
the pointer in the subprog as PTR_TO_MEM, only permit it if the
subprog is guaranteed not to mutate the packet.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_