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 crede…

published 2009-10-30 17 y ago modified 2026-06-16 4 mo ago also EUVD-2009-3604

cvss: 7.8; version 2.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 3.5%; EPSS 3.5% chance of exploitation in 30 days, percentile 89%
public exploits: 0; none known

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.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2009-3623 updated 2025-11-21 cvss 8.3

kernel: nfsd4: fix null dereference creating nfsv4 callback client

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.47% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	2.0	7.8	AV:N/AC:L/Au:N/C:N/I:N/A:C

Classification

Weakness

CWE-287 Improper Authentication

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2009-3623
NVD CVE-2009-3623

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary