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CVE-2021-3671

23
FAUCET Score

CVE-2021-3671 describes a null pointer dereference vulnerability in the Samba Kerberos server, specifically impacting how it handles missing sname in TGS-REQ. An authenticated user can exploit this flaw to crash the Samba server, affecting products like Debian and NetApp. With a CVSS score of 6.5 (MEDIUM), the vulnerability is network-exploitable with low attack complexity and requires low privileges, leading to high availability impact. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.13.12CPE matchmatch criteria
cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
>= 4.14.0, < 4.14.8CPE matchmatch criteria
cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
11.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:netapp:management_services_for_element_software:-:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.02%
Probability of exploitation in next 30 days
EPSS Percentile
79.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0203 is in the 91st percentile among its peer group of 21,977 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

github_advisorypatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: 16864-17084Fixed in: 4.18.3-1
microsoftpatch availablevia msrc
Product: azl3 samba 4.18.3-1 on Azure Linux 3.0Fixed in: 4.18.3-1
microsoftpatch availablevia msrc
Product: Azure Linux 3.0 x64Fixed in: 4.18.3-1
microsoftpatch availablevia msrc
Product: Azure Linux 3.0 ARMFixed in: 4.18.3-1

Vendor Advisories (3)

microsoft2024-Oct/CVE-2021-3671

CVE-2021-3671

Oct 8, 2024
microsoft2021-Oct/CVE-2021-3671Moderate

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.

Oct 12, 2021
redhatCVE-2021-3671Moderate

samba: Null pointer dereference on missing sname in TGS-REQ

Aug 31, 2021

References

bugzilla.redhat.com / show_bug.cgi
bugzilla.samba.org / show_bug.cgi
github.com / heimdal/heimdal/commit/04171147948d0a3636bc6374181926f0fb2ec83a
PatchThird Party Advisory
lists.debian.org / debian-lts-announce/2022/11/msg00034.html
Mailing ListThird Party Advisory
security.netapp.com / advisory/ntap-20221215-0002
Third Party Advisory
security.netapp.com / advisory/ntap-20230216-0008
Third Party Advisory
debian.org / security/2022/dsa-5287
Third Party Advisory