CWE-499: Serializable Class Containing Sensitive Data

Code Examples & CVEs

Demonstrative Examples

This code creates a new record for a medical patient:

This object does not explicitly deny serialization, allowing an attacker to serialize an instance of this object and gain a patient's name and Social Security number even though those fields are private.

BadJava

class PatientRecord {private String name;private String socialSecurityNum;public Patient(String name,String ssn) {this.SetName(name);this.SetSocialSecurityNumber(ssn);}}

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-499 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-499, Serializable Class Containing Sensitive Data, 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 Serializable Class Containing Sensitive Data during Implementation

MITRE associates mitigation with Implementation; documented detection approaches include Automated Static Analysis; recorded impacts include Read Application Data. Use these source-defined anchors to turn CWE-499 into implementation, review, and verification checks for the affected component.

CWE-499: Serializable Class Containing Sensitive Data — MITRE CWE

Triage CWE-499 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-499, Serializable Class Containing Sensitive Data, 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-499

Apply MITRE's full root-cause mapping guidance when using CWE-499, Serializable Class Containing Sensitive Data. 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-499 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-499, Serializable Class Containing Sensitive Data. 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-499: Serializable Class Containing Sensitive Data?+

CWE-499: Serializable Class Containing Sensitive Data is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The code contains a class with sensitive data, but the class does not explicitly deny serialization. The data can be accessed by serializing the class through another class. Serializable classes are effectively open classes since data cannot be hidden in them. Classes that do not explicitly deny serialization can be serialized by any other class, which can then in turn use the data stored inside it.

What are the security consequences of Serializable Class Containing Sensitive Data?+

If exploited, CWE-499 (Serializable Class Containing Sensitive Data) it can compromise Confidentiality, leading to outcomes such as Read Application Data.

How do you prevent or mitigate Serializable Class Containing Sensitive Data?+

Recommended mitigations for CWE-499 include: In Java, explicitly define final writeObject() to prevent serialization. This is the recommended solution. Define the writeObject() function to throw an exception explicitly denying serialization. Make sure to prevent serialization of your objects.

Which programming languages are affected by Serializable Class Containing Sensitive Data?+

CWE-499 commonly affects Java. 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-499 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-499: Serializable Class Containing Sensitive Data

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