Base weakness

Incomplete

CWE-523: Unprotected Transport of Credentials

Login pages do not use adequate measures to protect the user name and password while they are in transit from the client to the server.

Last updated May 1, 2026

20

Recorded CVEs

With this primary weakness

0

KEVs

In the CISA KEV catalog

Not rated

Likelihood of exploit

Per MITRE

Base

Abstraction

MITRE classification

Overview

CWE-523 (Unprotected Transport of Credentials) is a base-level software weakness catalogued by MITRE in the Common Weakness Enumeration (CWE). It describes a recurring type of mistake that can lead to exploitable security vulnerabilities.

Background

SSL (Secure Socket Layer) provides data confidentiality and integrity to HTTP. By encrypting HTTP messages, SSL protects from attackers eavesdropping or altering message contents.

Real-world CVEs

20 recorded CVEs are caused by CWE-523 (Unprotected Transport of Credentials). The highest-severity and most recent are shown first. 3 new CWE-523 CVEs have been recorded so far in 2026 (7 in 2025).

Showing 12 of 20 recorded CWE-523 CVEs. Track new ones as they are published and get AI-written analysis and fixes.

Monitor CWE-523 vulnerabilities

Common consequences

What can happen when CWE-523 is exploited.

Gain Privileges or Assume Identity

Affects: Access Control

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-523, grouped by where in the lifecycle they apply.

Operation

System Configuration

Enforce SSL use for the login page or any page used to transmit user credentials or other sensitive information. Even if the entire site does not use SSL, it MUST use SSL for login. Additionally, to help prevent phishing attacks, make sure that SSL serves the login page. SSL allows the user to verify the identity of the server to which they are connecting. If the SSL serves login page, the user can be certain they are talking to the proper end system. A phishing attack would typically redirect a user to a site that does not have a valid trusted server certificate issued from an authorized supplier.

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

Terminology & mappings

Mapped taxonomies

Software Fault Patterns: Exposed Data (SFP23)

Attack patterns

CAPEC attack patterns that exploit this weakness.

CAPEC-102: Session Sidejacking

Frequently asked questions

Common questions about CWE-523.

What is CWE-523?

Login pages do not use adequate measures to protect the user name and password while they are in transit from the client to the server.

What CVEs are caused by CWE-523?

20 recorded CVEs are attributed to CWE-523, including CVE-2025-57800, CVE-2025-64308, CVE-2025-64309.

How do you prevent CWE-523?

Enforce SSL use for the login page or any page used to transmit user credentials or other sensitive information. Even if the entire site does not use SSL, it MUST use SSL for login. Additionally, to help prevent phishing attacks, make sure that SSL serves the login page. SSL allows the user to verify the identity of the server to which they are connecting. If the SSL serves login page, the user can be certain they are talking to the proper end system. A phishing attack would typically redirect a user to a site that does not have a valid trusted server certificate issued from an authorized supplier.

How is CWE-523 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-523?

Exploiting CWE-523 can lead to: Gain Privileges or Assume Identity.

Is CWE-523 actively exploited?

20 recorded CVEs are caused by CWE-523; 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.

Stay ahead of CWE-523

Get alerted the moment a new CWE-523 vulnerability affects your stack, with AI-written analysis, severity context, and remediation guidance.

Start free See pricing

Background

Overview

Background

Real-world CVEs

Common consequences

How it happens

When it is introduced

How to prevent it

How to detect it

Automated Static Analysis

Related weaknesses

Parent

Can also be

Terminology & mappings

Mapped taxonomies

Attack patterns

Frequently asked questions

What is CWE-523?

What CVEs are caused by CWE-523?

How do you prevent CWE-523?

How is CWE-523 detected?

What are the consequences of CWE-523?

Is CWE-523 actively exploited?

References

Stay ahead of CWE-523