---
id: "CVE-2026-99051"
kind: "vulnerability"
aliases: ["CVE-2026-99051"]
title: "Linux kernel: fs-verity lookup can read freed memory across inodes"
severity: "unknown"
cvss: null
epss: 0.00198
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["fs-verity", "kernel", "linux", "runtime", "self-hosted"]
not_affected_if: ["no-fsverity-use"]
published_at: "2026-10-23T13:17:28+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-2026-99051", "first_seen_at": "2026-10-23T21:57:33+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-99051", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Linux kernel: fs-verity lookup can read freed memory across inodes

A race in the Linux kernel's fs-verity code frees verity metadata while another thread can still look it up under RCU, causing a use-after-free for a different inode. The sources give no severity, and the description does not state what an attacker can obtain beyond a memory-safety fault.

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

## How to check

- `uname -r` and compare against the fixed kernel release listed by your distribution's advisory for CVE-2026-99051
- Check whether fs-verity is in use: `unknown` from the sources; look for files enabled with `fsverity enable` or `fsverity measure` on your filesystems (ext4, f2fs, btrfs)

## Fix

- Update the Linux kernel to a release that includes the upstream commit 'fsverity: RCU-delay the freeing of struct fsverity_info'; exact version: unknown from the sources
- Reboot into the patched kernel after installing it

## Timeline

- 2026-10-23T21:57:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99051
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-99051

## From the sources

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

fsverity: RCU-delay the freeing of struct fsverity_info

__fsverity_get_info() calls rhashtable_lookup_fast(), which just uses
rcu_read_lock() and doesn't directly synchronize with
fsverity_remove_info().

For the same inode this isn't a problem: its fsverity_info is removed
only at inode eviction time or upon failure to enable verity, when the
inode no longer needs its fsverity_info and it will no longer be
accessed via that inode.

However, this is broken and can cause a use-after-free for concurrent
__fsverity_get_info() for *different* inodes.  Those rely on following
fsverity_info::rhash_head in the rhashtable under rcu_read_lock() only.
They also use fsverity_info::inode to do the key comparison.

Fix this by RCU-delaying the freeing of 'struct fsverity_info' after
it's been removed from the rhashtable.

---

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