What is the CVSS score of CVE-2021-3672?

CVE-2021-3672 has a CVSS 3.1 base score of 5.6 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L. EPSS exploitation probability: 2.6%.

Is there a public PoC exploit available for CVE-2021-3672?

Yes, a public proof-of-concept exploit is available for CVE-2021-3672. Prioritise patching immediately. EPSS: 2.6%.

Is there a patch available for CVE-2021-3672?

Yes, a patch is available for CVE-2021-3672. Update the affected software to the latest version immediately.

C Ares CVE-2021-3672

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2021-11-23 secalert@redhat.com

XSS Node.js Red Hat Siemens C Ares Enterprise Linux Enterprise Linux Eus Enterprise Linux For Ibm Z Systems Enterprise Linux For Ibm Z Systems Eus Enterprise Linux For Power Little Endian Enterprise Linux For Power Little Endian Eus Enterprise Linux Server Aus Enterprise Linux Server Tus Enterprise Linux Server Update Services For Sap Solutions Enterprise Linux Workstation Fedora Pgbouncer Node Js Sinec Infrastructure Network Services Enterprise Linux Tus Enterprise Linux Computer Node Fedoraproject C Ares Project

5.6

CVSS 3.1 · NVD

View

Vulnerability Assessment

Weakness	CWE CWE-79 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization Output encoding, context-aware escaping MITRE ATT&CK 2 techniques across 2 tactics: Initial Access, Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 5.6 (MEDIUM). Attack characteristics: network attack vector, high complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.
Exploit ScenarioDerived	A remote attacker could inject malicious scripts into web pages viewed by other users by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

Patch available 2.6% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAI

A flaw was found in c-ares library, where a missing input validation check of host names returned by DNS (Domain Name Servers) can lead to output of wrong hostnames which might potentially lead to. Rated medium severity (CVSS 5.6), this vulnerability is remotely exploitable, no authentication required. Public exploit code available.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. A flaw was found in c-ares library, where a missing input validation check of host names returned by DNS (Domain Name Servers) can lead to output of wrong hostnames which might potentially lead to Domain Hijacking. The highest threat from this vulnerability is to confidentiality and integrity as well as system availability. Affected products include: C-Ares Project C-Ares, Fedoraproject Fedora, Redhat Enterprise Linux, Redhat Enterprise Linux Computer Node, Redhat Enterprise Linux Eus.

Know when C Ares gets its next vulnerability

Watch products and get an email when something new is published
Check this CVE against your own stack and servers
Exploit and PoC references, threat intelligence from 22 sources

Continue with Google Continue with GitHub

No credit card · 7-day full trial

Severity by source

NVD PRIMARY 5.6 MEDIUM

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

Low

DescriptionNVD

A flaw was found in c-ares library, where a missing input validation check of host names returned by DNS (Domain Name Servers) can lead to output of wrong hostnames which might potentially lead to Domain Hijacking. The highest threat from this vulnerability is to confidentiality and integrity as well as system availability.

Threat Intelligence Overview

EPSS Score

2.6%

Top 16% exploitable

Exploit

POC

Public exploit code exists

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC Yes

EPSS 2.6%

Patch available Yes

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +3

CVSS: +28

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Cross-Site Scripting MEDIUM

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

Affected Products (CPE)NVD

cpe:2.3:a:c-ares_project:c-ares:*:*:*:*:*:*:*:*

cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux:7.7:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_computer_node:1:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_eus:7.7:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_eus:8.1:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_eus:8.2:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_eus:8.4:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems:8.0:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_eus:8.1:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_eus:8.2:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_eus:8.4:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian:8.0:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_eus:8.1:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_eus:8.2:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_eus:8.4:*:*:*:*:*:*:*

cpe:2.3:o:redhat:enterprise_linux_server_aus:8.2:*:*:*:*:*:*:*

+ 15 more

More in C Ares

View all

CVE-2016-5180 CRITICAL Act Now

9.8 Oct 03

Heap-based buffer overflow in the ares_create_query function in c-ares 1.x before 1.12.0 allows remote attackers to caus

CVE-2017-1000381 HIGH This Week

7.5 Jul 07

The c-ares function `ares_parse_naptr_reply()`, which is used for parsing NAPTR responses, could be triggered to read me

CVE-2023-32067 HIGH This Week

7.5 May 25

c-ares is an asynchronous resolver library. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable,

CVE-2020-8277 HIGH This Week

7.5 Nov 19

A Node.js application that allows an attacker to trigger a DNS request for a host of their choice could trigger a Denial

CVE-2023-31147 MEDIUM This Month

6.5 May 25

c-ares is an asynchronous resolver library. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable

CVE-2023-31130 MEDIUM This Month

6.4 May 25

c-ares is an asynchronous resolver library. Rated medium severity (CVSS 6.4). No vendor patch available.

CVE-2025-62408 MEDIUM This Month

5.9 Dec 08

c-ares is an asynchronous resolver library. Versions 1.32.3 through 1.34.5 terminate a query after maximum attempts whe

CVE-2023-31124 LOW Monitor

3.7 May 25

c-ares is an asynchronous resolver library. Rated low severity (CVSS 3.7), this vulnerability is remotely exploitable, n

Same weakness CWE-79 – Cross-site Scripting (XSS)

View all

CVE-2020-3580 MEDIUM POC

6.1

CVE-2013-7389 MEDIUM POC

4.3

CVE-2021-25299 MEDIUM POC

6.1

CVE-2014-2120 MEDIUM

6.1

CVE-2023-40000 HIGH POC

8.3

CVE-2016-8581 MEDIUM POC

6.1

CVE-2013-5223 MEDIUM POC

5.4

CVE-2025-52367 MEDIUM POC

5.4

Same technique XSS

View all

CVE-2017-9248 CRITICAL POC

9.8

CVE-2013-1710 CRITICAL POC

10.0

CVE-2024-52875 HIGH POC

8.8

References

Advisories & patches

PATCH https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf REF https://bugzilla.redhat.com/show_bug.cgi?id=1988342 REF https://security.gentoo.org/glsa/202401-02 REF https://www.oracle.com/security-alerts/cpujul2022.html

Search Externally

GitHub PoC

Exploit-DB PacketStorm Snyk Rapid7 Nuclei Templates Trickest PoC

Back