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.

Published: 2016-08-01 Last update: 2026-05-06 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-3120 is rated Moderate Risk (58.2/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 4.32%). EPSS rose +1.06% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2016-3120

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-27 3.26% 4.32% +1.06%
2 2025-11-11 5.55% 3.26% -2.29%
3 2025-11-09 — 5.55% —

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-3120

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.0 MEDIUM
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]
4.0 2.0 MEDIUM
AV:N/AC:L/Au:S/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.0 2.9 [email protected]

Weakness enumeration for CVE-2016-3120

OS Trackers for CVE-2016-3120

vendor priority summary link
debian not yet assigned CVE-2016-3120 not yet assigned priority: Debian including 1 source packages (krb5), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-3120
redhat low — https://access.redhat.com/security/cve/CVE-2016-3120
suse low CVE-2016-3120 severity low: SUSE including 379 source package names (amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, amazon/suse-sles-15-sp1-chost-byos-v20220127-hvm-ssd-x86_64, …), 552 product×package rows across 68 product lines (HPE Helion OpenStack 8, SUSE Liberty Linux 7, … (68 product lines)): Fixed 266, Known Affected 157, Known Not Affected 129. https://www.suse.com/security/cve/CVE-2016-3120/
ubuntu medium CVE-2016-3120 medium priority: Ubuntu including 1 source packages (krb5), 15 status rows across 15 suites (artful, bionic, cosmic, disco, eoan, focal, groovy, hirsute, precise, trusty, upstream, wily, xenial, yakkety, zesty): not-affected 10, released 3, ignored 2. https://ubuntu.com/security/CVE-2016-3120

Affected software / configurations for CVE-2016-3120

Vendor Product Version Raw CPE
mit kerberos_5 1.13 cpe:2.3:a:mit:kerberos_5:1.13:*:*:*:*:*:*:*
mit kerberos_5 1.13.1 cpe:2.3:a:mit:kerberos_5:1.13.1:*:*:*:*:*:*:*
mit kerberos_5 1.13.2 cpe:2.3:a:mit:kerberos_5:1.13.2:*:*:*:*:*:*:*
mit kerberos_5 1.13.3 cpe:2.3:a:mit:kerberos_5:1.13.3:*:*:*:*:*:*:*
mit kerberos_5 1.13.4 cpe:2.3:a:mit:kerberos_5:1.13.4:*:*:*:*:*:*:*
mit kerberos_5 1.13.5 cpe:2.3:a:mit:kerberos_5:1.13.5:*:*:*:*:*:*:*
mit kerberos_5 1.13.6 cpe:2.3:a:mit:kerberos_5:1.13.6:*:*:*:*:*:*:*
mit kerberos_5 1.14 cpe:2.3:a:mit:kerberos_5:1.14:*:*:*:*:*:*:*
mit kerberos_5 1.14.1 cpe:2.3:a:mit:kerberos_5:1.14.1:*:*:*:*:*:*:*
mit kerberos_5 1.14.2 cpe:2.3:a:mit:kerberos_5:1.14.2:*:*:*:*:*:*:*

References for CVE-2016-3120

cvelogic Threat Intelligence