CWE-605: Multiple Binds to the Same Port

Extended Description

On most systems, a combination of setting the SO_REUSEADDR socket option, and a call to bind() allows any process to bind to a port to which a previous process has bound with INADDR_ANY. This allows a user to bind to the specific address of a server bound to INADDR_ANY on an unprivileged port, and steal its UDP packets/TCP connection.

Code Examples & CVEs

Demonstrative Examples

This code binds a server socket to port 21, allowing the server to listen for traffic on that port.

This code may result in two servers binding a socket to same port, thus receiving each other's traffic. This could be used by an attacker to steal packets meant for another process, such as a secure FTP server.

BadC

void bind_socket(void) {                                                     int server_sockfd;int server_len;struct sockaddr_in server_address;                                                        /*unlink the socket if already bound to avoid an error when bind() is called*/                                                        unlink("server_socket");server_sockfd = socket(AF_INET, SOCK_STREAM, 0);                            server_address.sin_family = AF_INET;server_address.sin_port = 21;server_address.sin_addr.s_addr = htonl(INADDR_ANY);server_len = sizeof(struct sockaddr_in);                            bind(server_sockfd, (struct sockaddr *) &s1, server_len);                      }

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-605 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-605, Multiple Binds to the Same Port, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Multiple Binds to the Same Port during Policy

MITRE associates mitigation with Policy; documented detection approaches include Automated Static Analysis; recorded impacts include Read Application Data. Use these source-defined anchors to turn CWE-605 into implementation, review, and verification checks for the affected component.

CWE-605: Multiple Binds to the Same Port — MITRE CWE

Triage CWE-605 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-605, Multiple Binds to the Same Port, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-605

Apply MITRE's full root-cause mapping guidance when using CWE-605, Multiple Binds to the Same Port. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-605 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-605, Multiple Binds to the Same Port. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-605: Multiple Binds to the Same Port?+

CWE-605: Multiple Binds to the Same Port is a Common Weakness Enumeration (CWE) entry maintained by MITRE. When multiple sockets are allowed to bind to the same port, other services on that port may be stolen or spoofed. On most systems, a combination of setting the SO_REUSEADDR socket option, and a call to bind() allows any process to bind to a port to which a previous process has bound with INADDR_ANY. This allows a user to bind to the specific address of a server bound to INADDR_ANY on an unprivileged port, and steal its UDP packets/TCP connection.

What are the security consequences of Multiple Binds to the Same Port?+

If exploited, CWE-605 (Multiple Binds to the Same Port) it can compromise Confidentiality and Integrity, leading to outcomes such as Read Application Data.

How do you prevent or mitigate Multiple Binds to the Same Port?+

Recommended mitigations for CWE-605 include: Restrict server socket address to known local addresses.

Which programming languages are affected by Multiple Binds to the Same Port?+

CWE-605 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-605 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-605: Multiple Binds to the Same Port

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