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NVD / CVE Program· CNA redhat

CVE-2021-3672: 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 o

Noroxi assessment

Priority: Monitor (action score 23/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 2.8% (FIRST EPSS); higher than 86.4% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: c-ares (AlmaLinux:8) 1.13.0-6.el8; c-ares-devel (AlmaLinux:8) 1.13.0-6.el8; nodejs (AlmaLinux:8) 1:12.22.5-1.module_el8.5.0+85+79a7b441, 1:12.22.5-1.module_el8.4.0+2529+af52a4c7.
  • Mentioned 4 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to c-ares (AlmaLinux:8) 1.13.0-6.el8; c-ares-devel (AlmaLinux:8) 1.13.0-6.el8; nodejs (AlmaLinux:8) 1:12.22.5-1.module_el8.5.0+85+79a7b441, 1:12.22.5-1.module_el8.4.0+2529+af52a4c7 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.6 · v3.1—No exploit Fix available
Published
Nov 23, 2021
Updated
Jun 17, 2026
EPSS
2.8% · 86th percentile

Report tools

JSON

Action score

23

Monitor

Low priority for now.

CVSS
22 / 40 · 5.6 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.8%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
c-ares projectc-ares
fedoraprojectfedora
redhatenterprise linux
redhatenterprise linux computer node
redhatenterprise linux eus
redhatenterprise linux for ibm z systems
redhatenterprise linux for ibm z systems eus
redhatenterprise linux for power little endian
redhatenterprise linux for power little endian eus
redhatenterprise linux server aus
redhatenterprise linux server tus
redhatenterprise linux server update services for sap solutions

and 5 more

Limit the impact of XSS

This is a cross-site scripting (XSS) vulnerability. A well-configured Content-Security-Policy doesn't fix it, but greatly reduces its impact. Check your site's CSP and other security headers for free.

Check security headers

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • nodejs node.js12.0.0 and later · up to 12.12.0 inclusive
  • nodejs node.js12.13.0 and later · before 12.22.5
  • nodejs node.js14.0.0 and later · up to 14.14.0 inclusive
  • nodejs node.js14.15.0 and later · before 14.17.5
  • nodejs node.js16.0.0 and later · before 16.6.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

  • n/a c-ares

    • c-ares 1.17.2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8c-aresbefore 1.13.0-6.el81.13.0-6.el8
AlmaLinux:8c-ares-develbefore 1.13.0-6.el81.13.0-6.el8
AlmaLinux:8nodejsbefore 1:12.22.5-1.module_el8.5.0+85+79a7b4411:12.22.5-1.module_el8.5.0+85+79a7b441
AlmaLinux:8nodejsbefore 1:12.22.5-1.module_el8.4.0+2529+af52a4c71:12.22.5-1.module_el8.4.0+2529+af52a4c7
AlmaLinux:8nodejs-develbefore 1:12.22.5-1.module_el8.4.0+2529+af52a4c71:12.22.5-1.module_el8.4.0+2529+af52a4c7
AlmaLinux:8nodejs-develbefore 1:12.22.5-1.module_el8.5.0+85+79a7b4411:12.22.5-1.module_el8.5.0+85+79a7b441
AlmaLinux:8nodejs-docsbefore 1:12.22.5-1.module_el8.4.0+2529+af52a4c71:12.22.5-1.module_el8.4.0+2529+af52a4c7
AlmaLinux:8nodejs-full-i18nbefore 1:12.22.5-1.module_el8.4.0+2529+af52a4c71:12.22.5-1.module_el8.4.0+2529+af52a4c7
AlmaLinux:8nodejs-full-i18nbefore 1:12.22.5-1.module_el8.5.0+85+79a7b4411:12.22.5-1.module_el8.5.0+85+79a7b441
AlmaLinux:8nodejs-nodemonbefore 2.0.3-1.module_el8.4.0+2521+c668cc9f2.0.3-1.module_el8.4.0+2521+c668cc9f
AlmaLinux:8nodejs-packagingbefore 23-3.module_el8.4.0+2522+3bd4276223-3.module_el8.4.0+2522+3bd42762
AlmaLinux:8nodejs-packagingbefore 23-3.module_el8.5.0+254+b4526b1623-3.module_el8.5.0+254+b4526b16
AlmaLinux:8nodejs-packagingbefore 17-3.module_el8.4.0+2521+c668cc9f17-3.module_el8.4.0+2521+c668cc9f
AlmaLinux:8nodejs-packagingbefore 17-3.module_el8.4.0+2224+b07ac28e17-3.module_el8.4.0+2224+b07ac28e
AlmaLinux:8nodejs-packagingbefore 17-3.module_el8.3.0+2023+d2377ea317-3.module_el8.3.0+2023+d2377ea3
AlmaLinux:8npmbefore 1:6.14.14-1.12.22.5.1.module_el8.5.0+85+79a7b4411:6.14.14-1.12.22.5.1.module_el8.5.0+85+79a7b441
AlmaLinux:8npmbefore 1:6.14.14-1.12.22.5.1.module_el8.4.0+2529+af52a4c71:6.14.14-1.12.22.5.1.module_el8.4.0+2529+af52a4c7
Alpine:v3.11c-aresfrom 1.0.0 · before 1.17.2-r01.17.2-r0
Alpine:v3.11nodejsbefore 12.22.5-r012.22.5-r0
Alpine:v3.13nodejsbefore 14.17.5-r014.17.5-r0
Debian:10c-aresbefore 1.14.0-1+deb10u11.14.0-1+deb10u1
Debian:12c-aresbefore 1.17.1-1.11.17.1-1.1
Debian:9c-aresbefore 1.12.0-1+deb9u21.12.0-1+deb9u2
openSUSE:Leap 15.2c-aresbefore 1.17.1+20200724-lp152.2.9.11.17.1+20200724-lp152.2.9.1

+79

Same product

c-ares project: all records

Other highest-scoring records for the same primary product.

Published before and after this one in the same product

  • Later →CVE-2023-31124May 25, 2023 · AutoTools does not set CARES_RANDOM_FILE during cross compilation
    14Monitor
  • Later →CVE-2023-31130May 25, 2023 · Buffer Underwrite in ares_inet_net_pton()
    25Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:c-ares1.13.0-6.el8 · AlmaLinux:8Package registry (OSV)
almalinux:c-ares-devel1.13.0-6.el8 · AlmaLinux:8Package registry (OSV)
almalinux:nodejs1:12.22.5-1.module_el8.4.0+2529+af52a4c7 · AlmaLinux:8Package registry (OSV)
almalinux:nodejs-devel1:12.22.5-1.module_el8.5.0+85+79a7b441 · AlmaLinux:8Package registry (OSV)
almalinux:nodejs-docs1:12.22.5-1.module_el8.4.0+2529+af52a4c7 · AlmaLinux:8Package registry (OSV)
almalinux:nodejs-full-i18n1:12.22.5-1.module_el8.5.0+85+79a7b441 · AlmaLinux:8Package registry (OSV)
almalinux:nodejs-nodemon2.0.3-1.module_el8.4.0+2521+c668cc9f · AlmaLinux:8Package registry (OSV)
almalinux:nodejs-packaging17-3.module_el8.4.0+2224+b07ac28e · AlmaLinux:8Package registry (OSV)
almalinux:npm1:6.14.14-1.12.22.5.1.module_el8.4.0+2529+af52a4c7 · AlmaLinux:8Package registry (OSV)
alpine:c-ares1.17.2-r0 · Alpine:v3.11Package registry (OSV)
alpine:nodejs12.22.5-r0 · Alpine:v3.11Package registry (OSV)
debian:c-ares1.17.1-1.1 · Debian:12Package registry (OSV)
opensuse:c-ares1.17.1+20200724-lp152.2.9.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:c-ares-tests1.17.1+20200724-lp152.2.9.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:nodejs1010.24.1-lp152.2.18.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:nodejs1212.22.5-lp152.3.18.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:nodejs1414.17.5-lp152.14.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:nodejs1616.6.2-2.2 · openSUSE:TumbleweedPackage registry (OSV)
red hat:rh-nodejs12-nodejs0:12.22.5-1.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs12-nodejs-debuginfo0:12.22.5-1.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs12-nodejs-devel0:12.22.5-1.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs12-nodejs-docs0:12.22.5-1.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs12-nodejs-nodemon0:2.0.3-5.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs12-npm0:6.14.14-12.22.5.1.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs14-nodejs0:14.17.5-1.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs14-nodejs-debuginfo0:14.17.5-1.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs14-nodejs-devel0:14.17.5-1.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs14-nodejs-docs0:14.17.5-1.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs14-nodejs-nodemon0:2.0.3-5.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)
red hat:rh-nodejs14-npm0:6.14.14-14.17.5.1.el7 · Red Hat:rhel_software_collections:3::el7Package registry (OSV)

+9

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
low · data can be read
Integrity
low · data or configuration can be modified
Availability
low · the service can be disrupted
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
Low
Availability impact
Low

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

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

nvd-primary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records