---
id: "CVE-2026-98937"
kind: "vulnerability"
aliases: ["CVE-2026-98937"]
title: "Linux perf: unprivileged users can capture kernel callchains without permission"
severity: "unknown"
cvss: null
epss: 0.00209
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "kernel", "linux", "local-users"]
not_affected_if: ["patched-kernel"]
published_at: "2026-10-23T13:17:14+00:00"
first_seen_at: "2026-10-23T21:57:33+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98937", "first_seen_at": "2026-10-23T21:57:33+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-98937", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Linux perf: unprivileged users can capture kernel callchains without permission

The Linux kernel's perf_event_open() checked kernel profiling privilege only when kernel sampling was requested, not when kernel callchains were requested. A local user without kernel profiling privilege could therefore collect kernel call stacks.

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

## How to check

- unknown

## Fix

- Update to a Linux kernel release that includes the upstream fix (perf/core: Check kernel access when kernel callchains are requested); the fixed version numbers are unknown from the sources.

## Timeline

- 2026-10-23T21:57:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98937
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-98937

## From the sources

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

perf/core: Check kernel access when kernel callchains are requested

perf_event_open() currently gates perf_allow_kernel() only on
!attr.exclude_kernel.

However, users can still request kernel callchain collection with
attr.exclude_callchain_kernel == 0 even when attr.exclude_kernel == 1.
That still requires kernel profiling privilege, but the existing check
does not enforce it.

Update the permission check to call perf_allow_kernel() when either
kernel sampling is requested or kernel callchains are requested.

This keeps permission checks aligned with requested data and prevents
unprivileged use of kernel callchain capture.

---

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