---
id: "CVE-2026-98611"
kind: "vulnerability"
aliases: ["CVE-2026-98611"]
title: "Linux kernel: BPF crypto kfunc reads past validated buffer size"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["bpf", "linux-kernel", "runtime"]
not_affected_if: []
published_at: "2026-10-18T16:17:13+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:21:24+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98611", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel: BPF crypto kfunc reads past validated buffer size

The Linux kernel's bpf_crypto_ctx_create() kfunc reads reserved fields of its params argument before checking the buffer size, so a BPF program can pass a shorter buffer. The kernel can then read memory beyond the region the verifier validated for that argument.

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

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98611

## From the sources

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

bpf: Check params size before reading reserved fields

bpf_crypto_ctx_create() is a kfunc whose second argument is declared
with the __sz annotation, so the verifier only guarantees that
params__sz bytes of params are valid.  The function nevertheless reads
params->reserved[0] and params->reserved[1] (offsets 14 and 15) before
comparing params__sz against the size of struct bpf_crypto_params, so a
BPF program can pass a shorter buffer and have the kernel read past the
region that was validated for it.

Move the size check in front of the reserved field reads.

---

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