---
id: "CVE-2026-98587"
kind: "vulnerability"
aliases: ["CVE-2026-98587"]
title: "Linux kernel: FireWire cdev race can move an isochronous resource backward"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["firewire", "infrastructure", "linux-kernel"]
not_affected_if: []
published_at: "2026-10-18T16:17:11+00:00"
first_seen_at: "2026-10-23T21:57:15+00:00"
updated_at: "2026-10-25T05:22:57+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98587", "first_seen_at": "2026-10-23T21:57:15+00:00"}]
---

# Linux kernel: FireWire cdev race can move an isochronous resource backward

A race between the FireWire character device work item and file descriptor release lets the iso_resource_auto client resource state move backward from deallocation to reallocation. The sources describe only the state-machine race and its fix, not a demonstrated code execution or data exposure path.

_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-2026-98587

## From the sources

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

firewire: cdev: fix back-transition for iso_resource_auto client resource

The todo member of iso_resource_auto structure represents the state of the
client resource and normally transitions in the following order:

    ISO_RES_AUTO_ALLOC -> ISO_RES_AUTO_REALLOC -> ISO_RES_AUTO_DEALLOC

However, concurrent access from the work item and the file descriptor
release function can cause the state to transition backwards from
ISO_RES_AUTO_DEALLOC to ISO_RES_AUTO_REALLOC.

Prevent the back-transition by checking the current state before
updating it in the work item.

---

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