How severe is CVE-2016-3120?

CVE-2016-3120 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2016-3120 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-3120?

CVE-2016-3120 primarily affects Mit Kerberos 5. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-3120?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2016-3120 published?

CVE-2016-3120 was published on 2016-08-01 and last updated on 2026-06-17.

CVE-2016-3120

CVE-2016-3120 is a medium-severity vulnerability in Mit Kerberos 5 with a CVSS 3.x base score of 6.5. 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-476.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 5% (91st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Mit Kerberos 5
Published: 2016-08-01
Last modified: 2026-06-17

Description

The validate_as_request function in kdc_util.c in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.13.6 and 1.4.x before 1.14.3, when restrict_anonymous_to_tgt is enabled, uses an incorrect client data structure, which allows remote authenticated users to cause a denial of service (NULL pointer dereference and daemon crash) via an S4U2Self request.

Frequently asked questions

What is CVE-2016-3120?: The validate_as_request function in kdc_util.c in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.13.6 and 1.4.x before 1.14.3, when restrict_anonymous_to_tgt is enabled, uses an incorrect client data structure, which allows remote authenticated users to cause a denial of service (NULL pointer dereference and daemon crash) via an S4U2Self request.
How severe is CVE-2016-3120?: CVE-2016-3120 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2016-3120 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-3120?: CVE-2016-3120 primarily affects Mit Kerberos 5. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-3120?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2016-3120 published?: CVE-2016-3120 was published on 2016-08-01 and last updated on 2026-06-17.

References

Affected products (10)

cpe:2.3:a:mit:kerberos_5:1.13:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.13.1:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.13.2:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.13.3:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.13.4:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.13.5:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.13.6:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.14:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.14.1:*:*:*:*:*:*:*
cpe:2.3:a:mit:kerberos_5:1.14.2:*:*:*:*:*:*:*

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