Code execution via malformed DNS hostnames
Published Aug 16, 2021 · Updated Apr 30, 2025
Improper DNS hostname validation in Node.js before 12.22.5, 14.17.5, and 16.6.2 allows remote attackers to execute code. The bundled c-ares resolver accepts atypical characters in DNS-returned hostnames without validating or terminating them correctly, causing applications to consume wrong or attacker-controlled names. Exploitation requires an application to process an attacker-influenced DNS result; consequences include domain hijacking, injection, XSS, process crashes, and code execution.
Summary
What happened
Improper DNS hostname validation in Node.js before 12.22.5, 14.17.5, and 16.6.2 allows remote attackers to execute code. The bundled c-ares resolver accepts atypical characters in DNS-returned hostnames without validating or terminating them correctly, causing applications to consume wrong or attacker-controlled names. Exploitation requires an application to process an attacker-influenced DNS result; consequences include domain hijacking, injection, XSS, process crashes, and code execution.
The record
- CVE
- CVE-2021-22931
- Published
- Aug 16, 2021
- Updated
- Apr 30, 2025
- Vendor
- Node.js
- Product
- Node.js
- Classifications
- CWE-20, CWE-170
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 16, 2021CVE publishedPublication date reported by the CVE source.
- Apr 30, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0 <10.*
- Affected versionversion=11.0 <11.*
- Affected versionversion=12.0 <12.22.5
- Affected versionversion=13.0 <13.*
- Affected versionversion=14.0 <14.17.5
- Affected versionversion=15.0 <15.*
- Affected versionversion=16.0 <16.6.2
- Affected versionversion=4.0 <4.*
- Affected versionversion=5.0 <5.*
- Affected versionversion=6.0 <6.*
- Affected versionversion=7.0 <7.*
- Affected versionversion=8.0 <8.*
- Affected versionversion=9.0 <9.*
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Malformed DNS hostname proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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