---
id: "CVE-2026-98552"
kind: "vulnerability"
aliases: ["CVE-2026-98552"]
title: "Linux kernel perf: refcount leak in attach_perf_ctx_data race"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["kernel", "linux", "perf", "runtime"]
not_affected_if: []
published_at: "2026-10-18T16:17:07+00:00"
first_seen_at: "2026-10-23T21:57:15+00:00"
updated_at: "2026-10-25T05:23:29+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98552", "first_seen_at": "2026-10-23T21:57:15+00:00"}]
---

# Linux kernel perf: refcount leak in attach_perf_ctx_data race

A race between global and per-task perf context attachment in the Linux kernel's perf subsystem can leak a reference count. The sources describe a resource leak and do not state any code execution or data exposure.

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

## How to check

- unknown

## Fix

- unknown

## Timeline

- 2026-10-23T21:57:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98552

## From the sources

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

perf/core: Fix a refcount leak in attach_perf_ctx_data()

The attach_perf_ctx_data() can race on global and !global cases.  The
global case is protected by global_ctx_data_rwsem and shares a single
reference count using perf_ctx_data.global field.

But when it races with !global case, it may miss to set the global field
and result in a reference count leak.

 CPU1                                  CPU2
 ----------------------------------------------------------------
 attach_task_ctx_data(.global=1)       attach_task_ctx_data(.global=0)
   cd1 = alloc_perf_ctx_data();          cd2 = alloc_perf_ctx_data();
                                         //    { .global = 0, .refcount = 1 };

                                         try_cmpxchg(); // success,
                                         // task->perf_ctx_data = cd2
   try_cmpxhg(); // fail; old = cd2
   refcount_inc_not_zero(&old->refcount); // success
     // old.refcount = 2
   free_perf_ctx_data(cd1);

Then later detach_global_ctx_data() will see the data but it's not
marked as global, so it won't call detach_task_ctx_data().

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