How severe is CVE-2009-3623?

CVE-2009-3623 has a CVSS 2.0 base score of 7.8, rated high severity.

Is CVE-2009-3623 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-3623?

CVE-2009-3623 primarily affects Linux Linux Kernel. In total, 317 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-3623?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2009-3623 published?

CVE-2009-3623 was published on 2009-10-30 and last updated on 2026-06-16.

CVE-2009-3623

CVE-2009-3623 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 2.0 base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Severity: High (CVSS 2.0 base score 7.8)
EPSS exploit prediction: 3% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Linux Linux Kernel
Published: 2009-10-30
Last modified: 2026-06-16

Description

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.

Frequently asked questions

What is CVE-2009-3623?: 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.
How severe is CVE-2009-3623?: CVE-2009-3623 has a CVSS 2.0 base score of 7.8, rated high severity.
Is CVE-2009-3623 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-3623?: CVE-2009-3623 primarily affects Linux Linux Kernel. In total, 317 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-3623?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2009-3623 published?: CVE-2009-3623 was published on 2009-10-30 and last updated on 2026-06-16.

References

Affected products (317)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.0:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.1:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.2:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.3:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.4:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.5:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.6:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.7:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.8:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.8.1:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.9:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.10:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.1:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.2:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.3:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.4:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.5:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.6:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.7:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.8:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.9:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.10:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.11:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.11.12:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12.1:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12.2:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12.3:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12.4:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12.5:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12.6:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.13:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.13.1:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.13.2:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.13.3:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.13.4:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.13.5:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.14:*:*:*:*:*:*:*

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