CVE-2009-3623

What it is

The lookup_cb_cred function in fs/nfsd/nfs4callback.c in the nfsd4 subsystem in the Linux kernel before 2.6.31.2 attempts to access a credentials cache even when a client specifies the AUTH_NULL authentication flavor, which allows remote attackers to cause a denial of service (NULL pointer dereference and system crash) via an NFSv4 mount request.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

3.5% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2009-10-09 00:00 UTC ReservedThe CVE id was reserved by its CNA
2. 2009-10-30 20:30 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-06-16 23:12 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 3.5% in the next 30 days (EPSS).
• Severity: 7.8 HIGH (CVSS).
• Fix: none linked yet, which raises it.

Details

Published

2009-10-30 20:30 UTC

Last modified

2026-06-16 23:12 UTC

Exploit probability

3.5% · EPSS, next 30 days

Weakness

CWE-287 · Improper authentication

Record status

Modified

Affected

• Linux Kernel ≤ 2.6.31.1
• Linux Kernel 2.6.0
• Linux Kernel 2.6.1
• Linux Kernel 2.6.2
• Linux Kernel 2.6.3
• Linux Kernel 2.6.4
• Linux Kernel 2.6.5
• Linux Kernel 2.6.6

Attack profile CVSS 2.0 · 7.8

Attack vector

Network

Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Complete

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-2009-3623.md and follow it. Check whether this project is affected by CVE-2009-3623. 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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