CVE-2021-3671

A null pointer de-reference was found in the way samba kerberos server handled missing sname in TGS-REQ (Ticket Granting Server - Request). An authenticated user could use this flaw to crash the samba server.

Published: 2021-10-12 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-3671 is rated Moderate Risk (50.3/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.02%). 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-2021-3671

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 2026-06-15 5.14% 2.02% -3.11%
2 2026-05-30 3.01% 5.14% +2.13%
3 2026-03-26 — 3.01% —

Full EPSS history (26 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3671

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/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-2021-3671

OS Trackers for CVE-2021-3671

vendor priority summary link
alpine medium CVE-2021-3671: 2 source package rows (heimdal, samba); 111 state rows across 9 repos (3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 14, open 97. https://security.alpinelinux.org/vuln/CVE-2021-3671
debian not yet assigned CVE-2021-3671 not yet assigned priority: Debian including 2 source packages (heimdal, samba), 10 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 10. https://security-tracker.debian.org/tracker/CVE-2021-3671
redhat medium — https://access.redhat.com/security/cve/CVE-2021-3671
suse medium CVE-2021-3671 severity moderate: SUSE including 142 source package names (ctdb, libasn1-8-7.8.0-1.1, …), 1256 product×package rows across 44 product lines (HPE Helion OpenStack 8, SUSE CaaS Platform 4.0, … (44 product lines)): Known Not Affected 1166, Fixed 90. https://www.suse.com/security/cve/CVE-2021-3671/
ubuntu low CVE-2021-3671 low priority: Ubuntu including 2 source packages (heimdal, samba), 30 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): released 18, not-affected 8, ignored 2, needed 2. https://ubuntu.com/security/CVE-2021-3671

Affected software / configurations for CVE-2021-3671

Vendor Product Version Raw CPE
samba samba < 4.13.12 cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
samba samba >= 4.14.0, < 4.14.8 cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
netapp management_services_for_element_software — cpe:2.3:a:netapp:management_services_for_element_software:-:*:*:*:*:*:*:*
netapp management_services_for_netapp_hci — cpe:2.3:a:netapp:management_services_for_netapp_hci:-:*:*:*:*:*:*:*
netapp ontap_select_deploy_administration_utility — cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*

References for CVE-2021-3671

cvelogic Threat Intelligence