What CVEs are caused by CWE-350?

20 recorded CVEs are attributed to CWE-350, including CVE-2026-1490, CVE-2023-52235, CVE-2021-34561.

What are the consequences of CWE-350?

Exploiting CWE-350 can lead to: Gain Privileges or Assume Identity, Bypass Protection Mechanism.

Is CWE-350 actively exploited?

20 recorded CVEs are caused by CWE-350; none are currently in CISA's KEV catalog of actively exploited flaws.

Variant weakness

Draft

CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action

The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.

Last updated May 1, 2026

Recorded CVEs

With this primary weakness

KEVs

In the CISA KEV catalog

Not rated

Likelihood of exploit

Per MITRE

Variant

Abstraction

MITRE classification

Overview

Since DNS names can be easily spoofed or misreported, and it may be difficult for the product to detect if a trusted DNS server has been compromised, DNS names do not constitute a valid authentication mechanism. When the product performs a reverse DNS resolution for an IP address, if an attacker controls the DNS server for that IP address, then the attacker can cause the server to return an arbitrary hostname. As a result, the attacker may be able to bypass authentication, cause the wrong hostname to be recorded in log files to hide activities, or perform other attacks. Attackers can spoof DNS names by either (1) compromising a DNS server and modifying its records (sometimes called DNS cache poisoning), or (2) having legitimate control over a DNS server associated with their IP address.

Real-world CVEs

20 recorded CVEs are caused by CWE-350 (Reliance on Reverse DNS Resolution for a Security-Critical Action). The highest-severity and most recent are shown first. 6 new CWE-350 CVEs have been recorded so far in 2026 (4 in 2025).

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Common consequences

What can happen when CWE-350 is exploited.

Gain Privileges or Assume Identity, Bypass Protection Mechanism

Affects: Access Control

Malicious users can fake authentication information by providing false DNS information.

How it happens

When it is introduced

Typically introduced during these phases of the software lifecycle.

Architecture and Design

How to prevent it

Practical mitigations for CWE-350, grouped by where in the lifecycle they apply.

Architecture and Design

Use other means of identity verification that cannot be simply spoofed. Possibilities include a username/password or certificate.

Implementation

Perform proper forward and reverse DNS lookups to detect DNS spoofing.

How to detect it

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Effectiveness: High

Code examples

Illustrative examples from MITRE showing how the weakness appears in code.

The following code samples use a DNS lookup in order to decide whether or not an inbound request is from a trusted host. If an attacker can poison the DNS cache, they can gain trusted status.

Vulnerable example

struct hostent *hp;struct in_addr myaddr;

Vulnerable example

java

String ip = request.getRemoteAddr();

Vulnerable example

csharp

IPAddress hostIPAddress = IPAddress.Parse(RemoteIpAddress);

IP addresses are more reliable than DNS names, but they can also be spoofed. Attackers can easily forge the source IP address of the packets they send, but response packets will return to the forged IP address. To see the response packets, the attacker has to sniff the traffic between the victim machine and the forged IP address. In order to accomplish the required sniffing, attackers typically attempt to locate themselves on the same subnet as the victim machine. Attackers may be able to circumvent this requirement by using source routing, but source routing is disabled across much of the Internet today. In summary, IP address verification can be a useful part of an authentication scheme, but it should not be the single factor required for authentication.

In these examples, a connection is established if a request is made by a trusted host.

Vulnerable example

sd = socket(AF_INET, SOCK_DGRAM, 0);

Vulnerable example

java

while(true) {

These examples check if a request is from a trusted host before responding to a request, but the code only verifies the hostname as stored in the request packet. An attacker can spoof the hostname, thus impersonating a trusted client.

Illustrative examples

Real CVEs that MITRE cites as examples of this weakness.

CVE-2001-1488 — Does not do double-reverse lookup to prevent DNS spoofing.
CVE-2001-1500 — Does not verify reverse-resolved hostnames in DNS.
CVE-2000-1221 — Authentication bypass using spoofed reverse-resolved DNS hostnames.
CVE-2002-0804 — Authentication bypass using spoofed reverse-resolved DNS hostnames.
CVE-2001-1155 — Filter does not properly check the result of a reverse DNS lookup, which could allow remote attackers to bypass intended access restrictions via DNS spoofing.
CVE-2004-0892 — Reverse DNS lookup used to spoof trusted content in intermediary.
CVE-2003-0981 — Product records the reverse DNS name of a visitor in the logs, allowing spoofing and resultant XSS.

Terminology & mappings

Mapped taxonomies

PLOVER: Improperly Trusted Reverse DNS
CLASP: Trusting self-reported DNS name
Software Fault Patterns: Faulty endpoint authentication (SFP29)

Attack patterns

CAPEC attack patterns that exploit this weakness.

Frequently asked questions

Common questions about CWE-350.

What is CWE-350?: The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.
What CVEs are caused by CWE-350?: 20 recorded CVEs are attributed to CWE-350, including CVE-2026-1490, CVE-2023-52235, CVE-2021-34561.
How do you prevent CWE-350?: Use other means of identity verification that cannot be simply spoofed. Possibilities include a username/password or certificate.
How is CWE-350 detected?: Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
What are the consequences of CWE-350?: Exploiting CWE-350 can lead to: Gain Privileges or Assume Identity, Bypass Protection Mechanism.
Is CWE-350 actively exploited?: 20 recorded CVEs are caused by CWE-350; none are currently in CISA's KEV catalog of actively exploited flaws.

References

Weakness data is sourced from the MITRE CWE catalog (v4.20). CVE associations are aggregated and kept current by RadicalNotion.AI.

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Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

How to prevent it

How to detect it

Automated Static Analysis

Code examples

Illustrative examples

Related weaknesses

Parent

Can precede

Terminology & mappings

Mapped taxonomies

Attack patterns

Frequently asked questions

References

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