CVE-2021-47507

What it is

In the Linux kernel, the following vulnerability has been resolved: nfsd: Fix nsfd startup race (again) Commit bd5ae9288d64 ("nfsd: register pernet ops last, unregister first") has re-opened rpc_pipefs_event() race against nfsd_net_id registration (register_pernet_subsys()) which has been fixed by commit bb7ffbf29e76 ("nfsd: fix nsfd startup race triggering BUG_ON"). Restore the order of register_pernet_subsys() vs register_cld_notifier(). Add WARN_ON() to prevent a future regression. Crash info: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000012 CPU: 8 PID: 345 Comm: mount Not tainted 5.4.144-... #1 pc : rpc_pipefs_event+0x54/0x120 [nfsd] lr : rpc_pipefs_event+0x48/0x120 [nfsd] Call trace: rpc_pipefs_event+0x54/0x120 [nfsd] blocking_notifier_call_chain rpc_fill_super get_tree_keyed rpc_fs_get_tree vfs_get_tree do_mount ksys_mount __arm64_sys_mount el0_svc_handler el0_svc

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2024-05-24 15:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 04:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 4.7 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2024-05-24 15:15 UTC

Last modified

2026-06-17 04:17 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-362 · Race condition

Record status

Analyzed

Affected

• Linux Kernel < 5.4.165
• Linux Kernel < 5.10.85
• Linux Kernel < 5.15.8
• Linux Kernel 5.16

Attack profile CVSS 3.1 · 4.7

Attack vector

Local

Complexity

High

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-47507.md and follow it. Check whether this project is affected by CVE-2021-47507. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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